Citations
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This panel provides information on past usage of this interatomic potential (IP) powered by the OpenKIM Deep Citation framework. The word cloud indicates typical applications of the potential. The bar chart shows citations per year of this IP (bars are divided into articles that used the IP (green) and those that did not (blue)). The complete list of articles that cited this IP is provided below along with the Deep Citation determination on usage. See the Deep Citation documentation for more information.
77 Citations (13 used)
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USED (high confidence) M. Chrysos and H. Piel, “On the thermophysical and transport properties of 3He and 4He: A bubble interaction potential versus state of the art.,” The Journal of chemical physics. 2017. link Times cited: 2 Abstract: Three keynote thermophysical and transport properties of 3He… read moreAbstract: Three keynote thermophysical and transport properties of 3He and 4He, namely, the second virial coefficient, the shear viscosity, and the thermal conductivity, are reported for the "extended Dirac bubble potential" (EDbp), a novel model for He-He [M. Chrysos, J. Chem. Phys. 146, 024106 (2017)]. Comparisons with the experiment as well as with potentials with a proven track record and with the oversimplified Dbp are being made in the range 0.1-500 K to analyze the performance of the EDbp, which is shown here to emerge as a promising analytic model for He-He. A flowchart of how to treat the "buffer" in scattering cross section measurements is designed and conducted, offering a route to EDbp optimization. An impressive consistency with state-of-the-art calculations (which is just striking for such a simple analytic model) is found, essentially thanks to the performance of the phase-shift expression cotδl = λkr0ξlyl(kr0)-yl(krc)λkr0ξljl(kr0)-jl(krc), ξl=jl(kr0)yl(krc)-jl(krc)yl(kr0). A Multimedia view of δl(k,rc) versus k and rc is part of the material presented in this article. Data for the "best" rc(k) is given as a supplementary material. read less USED (low confidence) P. Xu, Q. Luo, B. Dong, and B. Song, “Simulations of the thermodynamic properties of the helium fluid from the state-of-the-art
ab initio
potentials and their uncertainty estimation,” Molecular Simulation. 2023. link Times cited: 0 USED (low confidence) P. Ströker, R. Hellmann, and K. Meier, “Thermodynamic properties of krypton from Monte Carlo simulations using ab initio potentials.,” The Journal of chemical physics. 2022. link Times cited: 2 Abstract: Ten different thermodynamic properties of the noble gas kryp… read moreAbstract: Ten different thermodynamic properties of the noble gas krypton were calculated by Monte Carlo simulations in the isothermal-isobaric ensemble using a highly accurate ab initio pair potential, Feynman-Hibbs corrections for quantum effects, and an extended Axilrod-Teller-Muto potential to account for nonadditive three-body interactions. Fourteen state points at a liquid and a supercritical isotherm were simulated. To obtain results representative for macroscopic systems, simulations with several particle numbers were carried out and extrapolated to the thermodynamic limit. Our results agree well with experimental data from the literature, an accurate equation of state for krypton, and a recent virial equation of state (VEOS) for krypton in the region where the VEOS has converged. These results demonstrate that very good agreement between simulation and experiment can only be achieved if nonadditive three-body interactions and quantum effects are taken into account. read less USED (low confidence) U. Deiters and R. Sadus, “Two-body interatomic potentials for He, Ne, Ar, Kr, and Xe from ab initio data.,” The Journal of chemical physics. 2019. link Times cited: 27 Abstract: A new method is reported for developing accurate two-body in… read moreAbstract: A new method is reported for developing accurate two-body interatomic potentials from existing ab initio data. The method avoids the computational complexity of alternative methods without sacrificing accuracy. Two-body potentials are developed for He, Ne, Ar, Kr, and Xe, which accurately reproduce the potential energy at all inter-atomic separations. Monte Carlo simulations of the pressure, radial distribution function, and isochoric heat capacity using the simplified potential indicate that the results are in very close, and sometimes almost indistinguishable, agreement with more complicated current state-of-the-art two-body potentials. read less USED (low confidence) F. Sharipov and F. Dias, “Temperature dependence of shock wave structure in helium and neon,” Physics of Fluids. 2019. link Times cited: 17 Abstract: Temperature dependence of a planar shock wave in helium and … read moreAbstract: Temperature dependence of a planar shock wave in helium and neon is studied by the direct simulation Monte Carlo method based on ab initio potentials. A quantum approach to interatomic interactions used here allows us to carry out calculations over a wide temperature range beginning from 1 K up to 5000 K. Moreover, for high temperatures, the quantum approach requires less computational effort than the classical one. Three gaseous species are considered: helium-3, helium-4, and neon. The problem is solved for three values of the Mach number Ma = 2, 5, 10. No influence of the quantum effects has been detected within the numerical error for the temperature of 300 K and higher. For temperatures lower than 300 K, the influence of the quantum effects in helium exceeds the numerical error and reaches 230%. In the case of neon, the quantum effect does not exceed 2% in the whole temperature range considered in the present work. A comparative analysis of flow-fields in shock waves at various temperatures points out a strong influence of the temperature ahead of a shock wave on its structure. The numerical data provided in the supplementary material can be used to model any flow of helium and neon in a wide range of temperatures.Temperature dependence of a planar shock wave in helium and neon is studied by the direct simulation Monte Carlo method based on ab initio potentials. A quantum approach to interatomic interactions used here allows us to carry out calculations over a wide temperature range beginning from 1 K up to 5000 K. Moreover, for high temperatures, the quantum approach requires less computational effort than the classical one. Three gaseous species are considered: helium-3, helium-4, and neon. The problem is solved for three values of the Mach number Ma = 2, 5, 10. No influence of the quantum effects has been detected within the numerical error for the temperature of 300 K and higher. For temperatures lower than 300 K, the influence of the quantum effects in helium exceeds the numerical error and reaches 230%. In the case of neon, the quantum effect does not exceed 2% in the whole temperature range considered in the present work. A comparative analysis of flow-fields in shock waves at various temperatures points out... read less USED (low confidence) F. Sharipov and F. Dias, “Structure of planar shock waves in gaseous mixtures based on ab initio direct simulation,” European Journal of Mechanics - B/Fluids. 2018. link Times cited: 7 USED (low confidence) A. Volkov and F. Sharipov, “Flow of a monatomic rarefied gas over a circular cylinder: Calculations based on the ab initio potential method,” International Journal of Heat and Mass Transfer. 2017. link Times cited: 10 USED (low confidence) F. Sharipov, “Ab initio simulation of gaseous mixture flow through an orifice,” Vacuum. 2017. link Times cited: 20 USED (low confidence) F. Sharipov and F. Dias, “Ab Initio Simulation of Shock Waves Propagating Through Gaseous Mixtures,” 31st International Symposium on Shock Waves 1. 2017. link Times cited: 0 USED (low confidence) F. Sharipov and F. Dias, “Ab initio simulation of planar shock waves,” Computers & Fluids. 2017. link Times cited: 11 USED (low confidence) F. Sharipov and J. L. Strapasson, “Ab initio simulation of rarefied gas flow through a thin orifice,” Vacuum. 2014. link Times cited: 22 USED (low confidence) J. L. Strapasson and F. Sharipov, “Ab initio simulation of heat transfer through a mixture of rarefied gases,” International Journal of Heat and Mass Transfer. 2014. link Times cited: 38 USED (low confidence) M. Abbaspour, E. Goharshadi, and M. N. Jorabchi, “Computation of some thermodynamic properties of helium–neon and helium–krypton fluid mixtures using molecular dynamics simulation,” Fluid Phase Equilibria. 2010. link Times cited: 3 NOT USED (low confidence) G. Garberoglio et al., “Ab Initio Calculation of Fluid Properties for Precision Metrology,” Journal of Physical and Chemical Reference Data. 2023. link Times cited: 4 Abstract: Recent advances regarding the interplay between ab initio ca… read moreAbstract: Recent advances regarding the interplay between ab initio calculations and metrology are reviewed, with particular emphasis on gas-based techniques used for temperature and pressure measurements. Since roughly 2010, several thermophysical quantities – in particular, virial and transport coefficients – can be computed from first principles without uncontrolled approximations and with rigorously propagated uncertainties. In the case of helium, computational results have accuracies that exceed the best experimental data by at least one order of magnitude and are suitable to be used in primary metrology. The availability of ab initio virial and transport coefficients contributed to the recent SI definition of temperature by facilitating measurements of the Boltzmann constant with unprecedented accuracy. Presently, they enable the development of primary standards of thermodynamic temperature in the range 2.5–552 K and pressure up to 7 MPa using acoustic gas thermometry, dielectric constant gas thermometry, and refractive index gas thermometry. These approaches will be reviewed, highlighting the effect of first-principles data on their accuracy. The recent advances in electronic structure calculations that enabled highly accurate solutions for the many-body interaction potentials and polarizabilities of atoms – particularly helium – will be described, together with the subsequent computational methods, most often based on quantum statistical mechanics and its path-integral formulation, that provide thermophysical properties and their uncertainties. Similar approaches for molecular systems, and their applications, are briefly discussed. Current limitations and expected future lines of research are assessed. read less NOT USED (low confidence) S. Dridi, M. Amar, M. Abderraba, and J. Passarello, “Development of a fully analytical equation of state using ab initio interaction potentials. Application to pure simple fluids: noble gases Ne, Ar, Kr, and Xe.,” Fluid Phase Equilibria. 2022. link Times cited: 4 NOT USED (low confidence) Y. Hu, Y. Zhai, H. Li, and F. McCourt, “Ab initio potential energy functions, spectroscopy and thermal physics for krypton-contained rare gas dimers,” Journal of Quantitative Spectroscopy and Radiative Transfer. 2022. link Times cited: 2 NOT USED (low confidence) U. Deiters and R. Sadus, “First-principles determination of the solid-liquid-vapor triple point: The noble gases.,” Physical review. E. 2022. link Times cited: 3 Abstract: We report first-principles calculations of the triple point … read moreAbstract: We report first-principles calculations of the triple point that allow us to predict the triple point temperature of atomic fluids to an accuracy that has not been previously possible. This is achieved by proposing a molecular simulation technique that can be used for solid-liquid equilibria at arbitrarily low pressures. It is demonstrated that the triple point is significantly influenced by the choice of two-body, three-body and quantum interactions. An improved theoretical understanding of triple points is important for both science in general, and metrology in particular, as it links the Boltzmann constant and the Kelvin temperature scale to fundamental constants. read less NOT USED (low confidence) P. J. Walker, T. Zhao, A. J. Haslam, and G. Jackson, “Ab initio development of generalized Lennard-Jones (Mie) force fields for predictions of thermodynamic properties in advanced molecular-based SAFT equations of state.,” The Journal of chemical physics. 2022. link Times cited: 5 Abstract: A methodology for obtaining molecular parameters of a modifi… read moreAbstract: A methodology for obtaining molecular parameters of a modified statistical associating fluid theory for variable-range interactions of Mie form (SAFT-VR Mie) equation of state (EoS) from ab initio calculations is proposed for non-associative species that can be modeled as single spherical segments. The methodology provides a strategy to map interatomic or intermolecular potentials obtained from ab initio quantum-chemistry calculations to the corresponding Mie potentials that can be used within the SAFT-VR Mie EoS. The inclusion of corrections for quantum and many-body effects allows for an excellent, fully predictive description of the vapor-liquid envelope and other bulk thermodynamic properties of noble gases; this description is of similar or superior quality to that obtained using SAFT-VR Mie with parameters regressed in the traditional way using experimental thermodynamic-property data. The methodology is extended to an anisotropic species, methane, where similar levels of accuracy are obtained. The efficacy of using less-accurate quantum-chemistry methods in this methodology is explored, showing that these methods do not provide satisfactory results, although we note that the description is nevertheless substantially better than those obtained using the conductor-like screening model for describing real solvents (COSMO-RS), the only other fully predictive ab initio method currently available. Overall, the reliance on thermophysical data is completely dispensed with, providing the first extensible, wholly predictive SAFT-type EoSs. read less NOT USED (low confidence) N. Gokul, A. Schultz, and D. Kofke, “Speed of Sound in Helium-4 from Ab Initio Acoustic Virial Coefficients,” Journal of Chemical & Engineering Data. 2021. link Times cited: 5 NOT USED (low confidence) R. Hellmann, C. Gaiser, B. Fellmuth, T. Vasyltsova, and E. Bich, “Thermophysical properties of low-density neon gas from highly accurate first-principles calculations and dielectric-constant gas thermometry measurements.,” The Journal of chemical physics. 2021. link Times cited: 13 Abstract: New interatomic potential energy and interaction-induced pol… read moreAbstract: New interatomic potential energy and interaction-induced polarizability curves for two ground-state neon atoms were developed and used to predict the second density, acoustic, and dielectric virial coefficients and the dilute gas shear viscosity and thermal conductivity of neon at temperatures up to 5000 K. The potential energy curve is based on supermolecular coupled-cluster (CC) calculations at very high levels up to CC with single, double, triple, quadruple, and perturbative pentuple excitations [CCSDTQ(P)]. Scalar and spin-orbit relativistic effects, the diagonal Born-Oppenheimer correction, and retardation of the dispersion interactions were taken into account. The interaction-induced polarizability curve, which in this work is only needed for the calculation of the second dielectric virial coefficient, is based on supermolecular calculations at levels up to CCSDT and includes a correction for scalar relativistic effects. In addition to these first-principles calculations, highly accurate dielectric-constant gas thermometry (DCGT) datasets measured at temperatures from 24.5 to 200 K were analyzed to obtain the difference between the second density and dielectric virial coefficients with previously unattained accuracy. The agreement of the DCGT values with the ones resulting from the first-principles calculations is, despite some small systematic deviations, very satisfactory. Apart from this combination of two virial coefficients, the calculated thermophysical property values of this work are significantly more accurate than any available experimental data. read less NOT USED (low confidence) A. Hogan and B. Space, “Next-Generation Accurate, Transferable, and Polarizable Potentials for Material Simulations.,” Journal of chemical theory and computation. 2020. link Times cited: 2 Abstract: PHAHST (potentials with high accuracy, high speed, and trans… read moreAbstract: PHAHST (potentials with high accuracy, high speed, and transferability) intermolecular potential energy functions have been developed from first principles for H2, N2, the noble gases, and a metal-organic material, HKUST-1. The potentials are designed from the outset to be transferable to heterogeneous environments including porous materials, interfaces, and material simulations. This is accomplished by theoretically justified choices for all functional forms, parameters, and mixing rules, including explicit polarization in every environment and fitting to high quality electronic structure calculations using methods that are tractable for real systems. The models have been validated in neat systems by comparison to second virial coefficients and bulk pressure-density isotherms. For inhomogeneous applications, our main target, comparisons are presented to previously published experimental studies on the metal-organic material HKUST-1 including adsorption, isosteric heats of adsorption, binding site locations, and binding site energies. A systematic prescription is provided for developing compatible potentials for additional small molecules and materials. The resulting models are recommended for use in complex heterogeneous simulations where existing potentials may be inadequate. read less NOT USED (low confidence) U. Deiters and R. Sadus, “Ab initio Interatomic Potentials and the Classical Molecular Simulation Prediction of the Thermophysical Properties of Helium.,” The journal of physical chemistry. B. 2020. link Times cited: 12 Abstract: The ability of modern ab initio potentials to predict the th… read moreAbstract: The ability of modern ab initio potentials to predict the thermophysical properties of helium is investigated. A new interatomic potential for helium is reported that is based on the latest available ab initio data and that is much more computationally efficient than other ab intio potentials, without sacrificing accuracy. The role of both two-body and three-body interactions is evaluated using classical Monte Carlo and molecular dynamics simulations. Data are reported for the second virial coefficient, vapor-liquid equilibria, acentric factor, compressibility factor, enthalpy, speed of sound and isobaric heat capacity. Three-body interactions have a minor influence on the properties of helium with the exception of the estimated critical properties. The influence of quantum particle behavior is relevant at temperatures typically below 200 K. For example, the experimental maximum in the isobaric heat capacities (along isobars) of helium is not observed in the classical simulations and can be attributed to quantum particle behavior. However, above this temperature helium behaves like a classical fluid and its thermodynamic properties can be adequately predicted by determining only two-body interactions. read less NOT USED (low confidence) A. Boese and G. Jansen, “ZMP-SAPT: DFT-SAPT using ab initio densities.,” The Journal of chemical physics. 2019. link Times cited: 6 Abstract: Symmetry Adapted Perturbation Theory (SAPT) has become an im… read moreAbstract: Symmetry Adapted Perturbation Theory (SAPT) has become an important tool when predicting and analyzing intermolecular interactions. Unfortunately, Density Functional Theory (DFT)-SAPT, which uses DFT for the underlying monomers, has some arbitrariness concerning the exchange-correlation potential and the exchange-correlation kernel involved. By using ab initio Brueckner Doubles densities and constructing Kohn-Sham orbitals via the Zhao-Morrison-Parr (ZMP) method, we are able to lift the dependence of DFT-SAPT on DFT exchange-correlation potential models in first order. This way, we can compute the monomers at the coupled-cluster level of theory and utilize SAPT for the intermolecular interaction energy. The resulting ZMP-SAPT approach is tested for small dimer systems involving rare gas atoms, cations, and anions and shown to compare well with the Tang-Toennies model and coupled cluster results. read less NOT USED (low confidence) R. Sadus, “Two-body intermolecular potentials from second virial coefficient properties.,” The Journal of chemical physics. 2019. link Times cited: 10 Abstract: A method is reported that enables second virial coefficient … read moreAbstract: A method is reported that enables second virial coefficient properties to be used to obtain relatively simple two-body intermolecular potentials. Generic n-m Lennard-Jones/Mie potentials are transformed into two-body potentials for neon, argon, krypton, and xenon. Comparison with results from highly accurate ab initio potentials indicates good agreement. A complete potential for real fluids is obtained by combining the two-body potentials with a density-dependent term for three-body interactions. Vapor-liquid equilibria molecular simulation data for the new potentials are compared with the experiment, which demonstrates the effectiveness of the two- and three-body contributions. The combination of the two-body 10-8 Lennard-Jones/Mie potential and three-body term is a good overall choice for the noble gases. read less NOT USED (low confidence) F. Sharipov, “Influence of quantum intermolecular interaction on internal flows of rarefied gases,” Vacuum. 2018. link Times cited: 12 NOT USED (low confidence) F. Sharipov and V. J. Benites, “Transport coefficients of helium-neon mixtures at low density computed from ab initio potentials.,” The Journal of chemical physics. 2017. link Times cited: 31 Abstract: The viscosity, thermal conductivity, diffusion coefficient, … read moreAbstract: The viscosity, thermal conductivity, diffusion coefficient, and thermal diffusion factor of helium-neon mixtures at low density are calculated for a wide range of temperature and for various molar fractions. The Chapman-Enskog method is employed considering the 10th order of the Sonine polynomial expansion. Ab initio potentials for intermolecular interactions are used to calculate the omega-integrals. The relative numerical error of the present results obtained for the potentials used here is less than 7 × 10-5 for the thermal diffusion factor and 2 × 10-5 for all the other coefficients. Since each employed potential has a different accuracy, the uncertainty related to such accuracies was analyzed, considering the contribution of each potential uncertainty. It was found that the total uncertainty due to the potentials is larger than the numerical error and it varies depending on the temperature and molar fraction. A comparison of the calculated transport coefficients with those available in the open literature shows that the present calculations provide the most accurate values currently available for the transport coefficients of helium-neon binary mixtures at low density. read less NOT USED (low confidence) B. Jäger and E. Bich, “Thermophysical properties of krypton-helium gas mixtures from ab initio pair potentials.,” The Journal of chemical physics. 2017. link Times cited: 18 Abstract: A new potential energy curve for the krypton-helium atom pai… read moreAbstract: A new potential energy curve for the krypton-helium atom pair was developed using supermolecular ab initio computations for 34 interatomic distances. Values for the interaction energies at the complete basis set limit were obtained from calculations with the coupled-cluster method with single, double, and perturbative triple excitations and correlation consistent basis sets up to sextuple-zeta quality augmented with mid-bond functions. Higher-order coupled-cluster excitations up to the full quadruple level were accounted for in a scheme of successive correction terms. Core-core and core-valence correlation effects were included. Relativistic corrections were considered not only at the scalar relativistic level but also using full four-component Dirac-Coulomb and Dirac-Coulomb-Gaunt calculations. The fitted analytical pair potential function is characterized by a well depth of 31.42 K with an estimated standard uncertainty of 0.08 K. Statistical thermodynamics was applied to compute the krypton-helium cross second virial coefficients. The results show a very good agreement with the best experimental data. Kinetic theory calculations based on classical and quantum-mechanical approaches for the underlying collision dynamics were utilized to compute the transport properties of krypton-helium mixtures in the dilute-gas limit for a large temperature range. The results were analyzed with respect to the orders of approximation of kinetic theory and compared with experimental data. Especially the data for the binary diffusion coefficient confirm the predictive quality of the new potential. Furthermore, inconsistencies between two empirical pair potential functions for the krypton-helium system from the literature could be resolved. read less NOT USED (low confidence) F. Sharipov and V. J. Benites, “Transport coefficients of helium-argon mixture based on ab initio potential.,” The Journal of chemical physics. 2015. link Times cited: 23 Abstract: The viscosity, thermal conductivity, diffusion coefficient, … read moreAbstract: The viscosity, thermal conductivity, diffusion coefficient, and thermal diffusion factor of helium-argon mixtures are calculated for a wide range of temperature and for various mole fractions up to the 12th order of the Sonine polynomial expansion with an ab initio intermolecular potential. The calculated values for these transport coefficients are compared with other data available in the open literature. The comparison shows that the obtained transport coefficients of helium-argon mixture have the best accuracy for the moment. read less NOT USED (low confidence) V. Sládek, L. Bučinský, J. Matúska, M. Ilcin, V. Lukes, and V. Laurinc, “Ab initio X(1)0(+) ground state potential curves of Pb···RG dimers (RG = He, Ne, Ar) including spin-orbit effects. Simulation of diffusion coefficients.,” Physical chemistry chemical physics : PCCP. 2014. link Times cited: 1 Abstract: CCSD(T) ground state potential curves of Pb···RG systems (RG… read moreAbstract: CCSD(T) ground state potential curves of Pb···RG systems (RG = He, Ne and Ar) are presented and the importance of the inclusion of spin-orbit effects is discussed. The closed-shell character of the Pb atom at the two-component relativistic level of relativistic theory leads to shallower potential energy curves compared to scalar relativistic open-shell calculations. The pressure-independent cross-diffusion coefficients pD12 have been simulated using the extrapolated two-component CCSD(T) ground state potential curves. The diffusion coefficients from scattering theory are compared with simulations based on molecular dynamics (MD) using the velocity autocorrelation function (VACF) and the Einstein equation. A correction for the proper assessment of the uncertainty in the VACF is proposed. The acceleration of the MD simulation of Pb in RG diffusion is proposed utilizing the RG in Pb diffusion. The dU[TQ]Z/CCSD(T) potential curve of Pb···He (De = 8.667 cm(-1), re = 4.683 Å) supports only one vibrational level. The anharmonicity of this potential is compared to the potential of He···He which also supports only one vibrational level. The comparison is based on the mean square separations of the vibrational wave function. read less NOT USED (low confidence) B. Song, X. Wang, K. Kang, and Z. Liu, “Highly accurate transport properties of helium-4, helium-3, and their binary mixtures by ab initio potential,” Cryogenics. 2014. link Times cited: 4 NOT USED (low confidence) G. Garberoglio, “On the contribution of non-additive three-body interactions to the third virial coefficient of para-hydrogen,” Chemical Physics Letters. 2013. link Times cited: 8 NOT USED (low confidence) B. Jäger, R. Hellmann, E. Bich, and E. Vogel, “Ab initio virial equation of state for argon using a new nonadditive three-body potential.,” The Journal of chemical physics. 2011. link Times cited: 85 Abstract: An ab initio nonadditive three-body potential for argon has … read moreAbstract: An ab initio nonadditive three-body potential for argon has been developed using quantum-chemical calculations at the CCSD(T) and CCSDT levels of theory. Applying this potential together with a recent ab initio pair potential from the literature, the third and fourth to seventh pressure virial coefficients of argon were computed by standard numerical integration and the Mayer-sampling Monte Carlo method, respectively, for a wide temperature range. All calculated virial coefficients were fitted separately as polynomials in temperature. The results for the third virial coefficient agree with values evaluated directly from experimental data and with those computed for other nonadditive three-body potentials. We also redetermined the second and third virial coefficients from the best experimental pρT data utilizing the computed higher virial coefficients as constraints. Thus, a significantly closer agreement of the calculated third virial coefficients with the experimental data was achieved. For different orders of the virial expansion, pρT data have been calculated and compared with results from high quality measurements in the gaseous and supercritical region. The theoretically predicted pressures are within the very small experimental errors of ±0.02% for p ≤ 12 MPa in the supercritical region near room temperature, whereas for subcritical temperatures the deviations increase up to +0.3%. The computed pressure at the critical density and temperature is about 1.3% below the experimental value. At pressures between 200 MPa and 1000 MPa and at 373 K, the calculated values deviate by 1% to 9% from the experimental results. read less NOT USED (low confidence) E. Vogel, “Reference Viscosities of Gaseous Methane and Hydrogen Sulfide at Low Density in the Temperature Range from (292 to 682) K,” Journal of Chemical & Engineering Data. 2011. link Times cited: 26 Abstract: An all-quartz oscillating-disk viscometer of very high preci… read moreAbstract: An all-quartz oscillating-disk viscometer of very high precision was used to measure the temperature dependence of the viscosities of methane and hydrogen sulfide at low densities. The measurements were based on a single calibration at room temperature with a value theoretically calculated using an accurate ab initio pair potential for helium and the kinetic theory of dilute monatomic gases. The uncertainty of the experimental data is conservatively estimated to be ± 0.15 % at room temperature increasing to ± 0.20 % at the highest temperature of 682 K. The new data are compared with experimental data from the literature as well as with values obtained from the Quinones-Cisneros correlation for methane (2010) and the Schmidt correlation for hydrogen sulfide (2008) both implemented in the REFPROP computer program of the National Institute of Standards and Technology (NIST). The comparison shows that the low-density values of the Quinones-Cisneros correlation for methane, primarily based on measurements in t... read less NOT USED (low confidence) K. Oleksy, F. Karlický, and R. Kalus, “Structures and energetics of helium cluster cations: equilibrium geometries revisited through the genetic algorithm approach.,” The Journal of chemical physics. 2010. link Times cited: 16 Abstract: Equilibrium geometries and dissociation energies of He(N)(+)… read moreAbstract: Equilibrium geometries and dissociation energies of He(N)(+) clusters have been calculated for N=3-35 using an extended genetic algorithm approach and a semiempirical model of intracluster interactions [P. J. Knowles, J. N. Murrell, and E. J. Hodge, Mol. Phys. 85, 243 (1995)]. A general aufbau principle is formulated for both ionic cores and neutral solvation shells, and the results are thoroughly compared with other theoretical data available for helium cluster cations in literature. read less NOT USED (low confidence) K. Szalewicz and B. Jeziorski, “Explicitly-correlated Gaussian geminals in electronic structure calculations,” Molecular Physics. 2010. link Times cited: 21 Abstract: Explicitly correlated functions have been used since 1929, b… read moreAbstract: Explicitly correlated functions have been used since 1929, but initially only for two-electron systems. In 1960, Boys and Singer showed that if the correlating factor is of Gaussian form, many-electron integrals can be computed for general molecules. The capability of explicitly correlated Gaussian (ECG) functions to accurately describe many-electron atoms and molecules was demonstrated only in the early 1980s when Monkhorst, Zabolitzky and the present authors cast the many-body perturbation theory (MBPT) and coupled cluster (CC) equations as a system of integro-differential equations and developed techniques of solving these equations with two-electron ECG functions (Gaussian-type geminals, GTG). This work brought a new accuracy standard to MBPT/CC calculations. In 1985, Kutzelnigg suggested that the linear r 12 correlating factor can also be employed if n-electron integrals, n > 2, are factorised with the resolution of identity. Later, this factor was replaced by more general functions f (r 12), most often by , usually represented as linear combinations of Gaussian functions which makes the resulting approach (called F12) a special case of the original GTG expansion. The current state-of-art is that, for few-electron molecules, ECGs provide more accurate results than any other basis available, but for larger systems the F12 approach is the method of choice, giving significant improvements over orbital calculations. read less NOT USED (low confidence) M. Przybytek et al., “Relativistic and quantum electrodynamics effects in the helium pair potential.,” Physical review letters. 2010. link Times cited: 110 Abstract: The helium pair potential was computed including relativisti… read moreAbstract: The helium pair potential was computed including relativistic and quantum electrodynamics contributions as well as improved accuracy adiabatic ones. Accurate asymptotic expansions were used for large distances R. Error estimates show that the present potential is more accurate than any published to date. The computed dissociation energy and the average R for the (4)He(2) bound state are 1.62+/-0.03 mK and 47.1+/-0.5 A. These values can be compared with the measured ones: 1.1(-0.2)(+0.3) mK and 52+/-4 A [R. E. Grisenti, Phys. Rev. Lett. 85, 2284 (2000)]. read less NOT USED (low confidence) J. Mehl, “Ab initio properties of gaseous helium,” Comptes Rendus Physique. 2009. link Times cited: 31 NOT USED (low confidence) A. Grigoriev, P. Grigoriev, and A. M. Dyugaev, “Surface Levels and Their Contribution to the Surface Tension of Quantum Liquids,” Journal of Low Temperature Physics. 2009. link Times cited: 2 NOT USED (low confidence) M. Przybytek and B. Jeziorski, “Higher dispersion coefficients for the interaction of helium atoms,” Chemical Physics Letters. 2008. link Times cited: 13 NOT USED (low confidence) K. AkshayKrishnaA., E. Wadbro, C. Köhler, P. Mitev, P. Broqvist, and J. Kullgren, “CCS: A software framework to generate two-body potentials using Curvature Constrained Splines,” Comput. Phys. Commun. 2021. link Times cited: 4 NOT USED (low confidence) K. Patkowski, “Chapter One - Benchmark Databases of Intermolecular Interaction Energies: Design, Construction, and Significance,” Annual Reports in Computational Chemistry. 2017. link Times cited: 8 NOT USED (low confidence) G. Raabe, “Molecular Models (Force Fields).” 2017. link Times cited: 0 NOT USED (low confidence) G. Guevara-Carrion, H. Hasse, and J. Vrabec, “Thermodynamic properties for applications in chemical industry via classical force fields.,” Topics in current chemistry. 2012. link Times cited: 26 NOT USED (high confidence) R. Sadus, “Combining intermolecular potentials for the prediction of fluid properties: Two-body and three-body interactions.,” The Journal of chemical physics. 2020. link Times cited: 2 Abstract: The ability to combine intermolecular potentials without los… read moreAbstract: The ability to combine intermolecular potentials without loss of information is investigated. Molecular simulation results for both vapor-liquid equilibria and supercritical isochoric heat capacities are reported for different combinations of n-m potentials. The role of both additional cohesion and repulsive terms is determined. The 12-8-6 potential obtained by adding an m = 6 contribution to the 12-8 potential significantly broadens the phase envelope, which remains inside of the 12-6 envelope. In contrast, the 12+9-6 potential that involves an additional n = 9 repulsive contribution lifts the phase envelope above the 12-6 values. The 12-8-6 potential significantly reduces the maximum and minimum observed for the isochoric heat capacity at supercritical conditions. In contrast, the additional repulsion of the 12+9-6 potential has a relatively small influence on the supercritical behavior of the isochoric heat capacity. Significantly, a comparison of vapor-liquid equilibria data for two-body only simulations for Ar, Kr, and Xe indicates that there is very good agreement with the 12-8-6 data. This means that the 12-8-6 potential may provide a useful description of two-body only interactions for the noble gases. The 12+9-8 potential at least partially reproduces vapor-liquid properties of noble gases interacting via two-body plus three-body interactions. In general, the combination of potentials provides a mechanism of simplifying the calculation of two-body and two-body plus three-body interactions. read less NOT USED (high confidence) H. Piel and M. Chrysos, “From Lippmann-Schwinger formulations to a general formula for absolute asymptotic scattering phase functions and shifts: a unified framework for potentials of any range,” Molecular Physics. 2020. link Times cited: 2 Abstract: Appropriately handling the Lippmann-Schwinger equation can b… read moreAbstract: Appropriately handling the Lippmann-Schwinger equation can bring substantial benefits in quantum scattering. Here, the advantages of a parametric equation for the system's normalised wavefunction, ψ, supplied with regular and irregular wavefunctions of a reference Hamiltonian for arbitrary subsystems are discussed to extend previous results [H. Piel and M. Chrysos, Mol. Phys., 116, 2364 (2018)] to any interaction-range for the effective and ‘excess’ V potentials. While the idea of using reference wavefunctions to solve scattering problems is not new [J. P. Burke, C. H. Greene, and J. L. Bohn, Phys. Rev. Lett. 81, 3355 (1998); B. P. Ruzic, C. H. Greene, and J. L. Bohn, Phys. Rev. A 87, 032706 (2013)], convincing evidence that a wide variety of problems can benefit from the careful choice of and and the demonstration of how their occurrence in a compact formula permits the absolute definition of asymptotic scattering phases are among our highlights. Various examples employing Coulomb-van-der-Waals interactions in helium, along with an insightful rephrasing of ideas originally introduced in quantum defect theory for ultracold alkali-alkali collisions are given, adding to the recognition of these works and further promoting the need for properly selected reference wavefunctions in scattering calculations. GRAPHICAL ABSTRACT read less NOT USED (high confidence) A. Császár, T. Szidarovszky, O. Asvany, and S. Schlemmer, “Fingerprints of microscopic superfluidity in HHen+ clusters,” Molecular Physics. 2019. link Times cited: 11 Abstract: ABSTRACT The structures and the vibrational dynamics of the … read moreAbstract: ABSTRACT The structures and the vibrational dynamics of the complexes HHe are investigated experimentally (via mass spectrometry (MS)) and at high levels of electronic-structure theory. The MS measurements reveal interesting trends about the stability of the starting members of the HHe family. The computations establish that the basically linear, strongly bound, symmetric triatomic molecular ion He(H)He, with an equilibrium H–He distance of 0.925 Å and about 2/3 but at least 1/2 of the positive charge on H, is the molecular core of all of the complexes. Definitive quantum-chemical results are obtained for HHe and HHe, including the proton affinity of He (computed to be cm−1 via the focal-point analysis (FPA) scheme), the FPA isomerisation energy between the two linear isomers of HHe ( cm−1), and the dissociation energy of the HHe HHe + He reaction, with an FPA estimate of cm−1. The structural isomers of the He-solvated complexes are discussed up to n=18. A useful notation, [k−l−m]-HHe, is introduced to characterise qualitatively the three possible belts around the He–H–He core in HHe (), where l denotes the number of He atoms in the central belt and denote the number of He atoms in the top and bottom belts. Capping He atoms attached to the belts can be indicated by sub- and superscripts. Several possible indicators of microscopic superfluidity are investigated: He evaporation energies, rotational constants, and vibrational fundamentals. GRAPHICAL ABSTRACT read less NOT USED (high confidence) A. Owens and V. Špirko, “Universal behavior of diatomic halo states and the mass sensitivity of their properties,” Journal of Physics B: Atomic, Molecular and Optical Physics. 2018. link Times cited: 4 Abstract: The scattering and spectroscopic properties of molecular hal… read moreAbstract: The scattering and spectroscopic properties of molecular halo states can serve as sensitive probes of the constancy of the electron-to-proton mass ratio β = m e / m p . Since halo states are formed by resonant s-wave interactions, their properties exhibit universal correlations that are fairly independent of the interactions at short distances. For diatomic molecules, these properties depend on a single-parameter only, and so this ‘universality’ means that all the characteristics of a diatomic halo state can be determined with high precision if only one-parameter is accurately known. Furthermore, this knowledge can be used to establish the respective property mass sensitivities for investigating the stability of β. Here, we show for the halo states of the helium dimers that the relationship between the probed properties and their mass sensitivity can be derived from numerically exact solutions of suitable radial Schrödinger equations for a set of effective potential energy curves. The resulting relations exhibit a weak dependence on the short-range part of the used potentials and a near-negligible dependence on the ‘higher-order’ nonadiabatic, relativistic, quantum electrodynamical and residual retardation effects. The presented approach is thus a robust alternative to other literature approaches, particularly in cases where a lack of experimental data prevents an accurate interaction potential from being determined. read less NOT USED (high confidence) H. Piel and M. Chrysos, “A shortcut to quantum-mechanical absolute scattering phase-shift computations in van der Waals systems,” Molecular Physics. 2018. link Times cited: 2 Abstract: ABSTRACT We discuss the advantages of a single-valued functi… read moreAbstract: ABSTRACT We discuss the advantages of a single-valued function (and related formula) for the absolute definition and computation of scattering phase shifts in spherically symmetric van der Waals potentials. Although the expression, as such, is known since the 2000s [K. Chadan, R. Kobayashi, and T. Kobayashi, J. Math. Phys. 42, 4031 (2001)], only little numerical evidence of its effectiveness has been available so far. Our effort, here, is to give this device the recognition it deserves and to make it more widely known as an alternative to standard methods. This is all the more interesting as in the standard approaches the access to absolute is not straightforward but needs additional operations to be performed. We show how the formula can be derived, as a consequence of variable-phase approaches from the two broadly accepted methods for , and compare its performance with these methods. He–He and two of its keynote thermophysical properties, namely, the 4He and 3He second virial and acoustic virial coefficients are being studied for the purpose. The use of absolute is mandatory for those coefficients. Other important points related to the concept of phase function and its connection with Volterra equation are given in Supplementary material. GRAPHICAL ABSTRACT read less NOT USED (high confidence) F. Sharipov, “Modeling of transport phenomena in gases based on quantum scattering,” Physica A: Statistical Mechanics and its Applications. 2018. link Times cited: 17 NOT USED (high confidence) P. T. Myatt, A. K. Dham, P. Chandrasekhar, F. McCourt, and R. L. Roy, “A new empirical potential energy function for Ar2,” Molecular Physics. 2018. link Times cited: 9 Abstract: ABSTRACT A critical re-analysis of all available spectroscop… read moreAbstract: ABSTRACT A critical re-analysis of all available spectroscopic and virial coefficient data for Ar2 has been used to determine an improved empirical analytic potential energy function that has been ‘tuned’ to optimise its agreement with viscosity, diffusion and thermal diffusion data, and whose short-range behaviour is in reasonably good agreement with the most recent ab initio calculations for this system. The recommended Morse/long-range potential function is smooth and differentiable at all distances, and incorporates both the correct theoretically predicted long-range behaviour and the correct limiting short-range functional behaviour. The resulting value of the well depth is cm−1 and the associated equilibrium distance is re = 3.766 (±0.002) Å, while the 40Ar s-wave scattering length is −714 Å. read less NOT USED (high confidence) L. Shirkov and V. Sládek, “Benchmark CCSD-SAPT study of rare gas dimers with comparison to MP-SAPT and DFT-SAPT.,” The Journal of chemical physics. 2017. link Times cited: 10 Abstract: Symmetry-adapted perturbation theory (SAPT) based on coupled… read moreAbstract: Symmetry-adapted perturbation theory (SAPT) based on coupled cluster approach with single and double excitations (CCSD) treatment of intramonomer electron correlation effects was applied to study rare gas homodimers from He2 to Kr2. The obtained benchmark CCSD-SAPT energies, including cumulant contributions to first order exchange and second-order exchange-induction terms, were then compared to their counterparts found using other methods-Møller-Plesset-SAPT based on many-body Møller-Plesset perturbation theory and DFT-SAPT based on density functional theory. The SAPT terms up to the second-order were calculated with the basis sets close to the complete basis set at the large range of interatomic distances R. It was shown that overestimation of the binding energies De found with DFT-SAPT reported in the work of Shirkov and Makarewicz [J. Chem. Phys. 142, 064102 (2015)] for Ar2 and Kr2 is mostly due to underestimation of the exchange energy Eexch(1) when comparing to the CCSD-SAPT benchmark. The CCSD-SAPT potentials were found to give the following values of the dissociation energies D0: 0.0006 cm-1 for He2, 16.71 cm-1 for Ne2, 85.03 cm-1 for Ar2, and 129.81 cm-1 for Kr2, which agree well with the values found from previously reported highly accurate ab initio supermolecular potentials and experimental data. The long-range dispersion coefficients C2n up to n = 6 that give the dispersion energy asymptotically equivalent to its SAPT counterpart were calculated from dynamic multipole polarizabilities at different levels of theory. read less NOT USED (high confidence) R. Hellmann, B. Jäger, and E. Bich, “State-of-the-art ab initio potential energy curve for the xenon atom pair and related spectroscopic and thermophysical properties.,” The Journal of chemical physics. 2017. link Times cited: 59 Abstract: A new ab initio interatomic potential energy curve for two g… read moreAbstract: A new ab initio interatomic potential energy curve for two ground-state xenon atoms is presented. It is based on supermolecular calculations at the coupled-cluster level with single, double, and perturbative triple excitations [CCSD(T)] employing basis sets up to sextuple-zeta quality, which were developed as part of this work. In addition, corrections were determined for higher coupled-cluster levels up to CCSDTQ as well as for scalar and spin-orbit relativistic effects at the CCSD(T) level. A physically motivated analytical function was fitted to the calculated interaction energies and used to compute the vibrational spectrum of the dimer, the second virial coefficient, and the dilute gas transport properties. The agreement with the best available experimental data for the investigated properties is excellent; the new potential function is superior not only to previous ab initio potentials but also to the most popular empirical ones. read less NOT USED (high confidence) M. Vlasiuk and R. Sadus, “Ab initio interatomic potentials and the thermodynamic properties of fluids.,” The Journal of chemical physics. 2017. link Times cited: 15 Abstract: Monte Carlo simulations with accurate ab initio interatomic … read moreAbstract: Monte Carlo simulations with accurate ab initio interatomic potentials are used to investigate the key thermodynamic properties of argon and krypton in both vapor and liquid phases. Data are reported for the isochoric and isobaric heat capacities, the Joule-Thomson coefficient, and the speed of sound calculated using various two-body interatomic potentials and different combinations of two-body plus three-body terms. The results are compared to either experimental or reference data at state points between the triple and critical points. Using accurate two-body ab initio potentials, combined with three-body interaction terms such as the Axilrod-Teller-Muto and Marcelli-Wang-Sadus potentials, yields systematic improvements to the accuracy of thermodynamic predictions. The effect of three-body interactions is to lower the isochoric and isobaric heat capacities and increase both the Joule-Thomson coefficient and speed of sound. The Marcelli-Wang-Sadus potential is a computationally inexpensive way to utilize accurate two-body ab initio potentials for the prediction of thermodynamic properties. In particular, it provides a very effective way of extending two-body ab initio potentials to liquid phase properties. read less NOT USED (high confidence) M. Vlasiuk and R. Sadus, “Predicting vapor-liquid phase equilibria with augmented ab initio interatomic potentials.,” The Journal of chemical physics. 2017. link Times cited: 13 Abstract: The ability of ab initio interatomic potentials to accuratel… read moreAbstract: The ability of ab initio interatomic potentials to accurately predict vapor-liquid phase equilibria is investigated. Monte Carlo simulations are reported for the vapor-liquid equilibria of argon and krypton using recently developed accurate ab initio interatomic potentials. Seventeen interatomic potentials are studied, formulated from different combinations of two-body plus three-body terms. The simulation results are compared to either experimental or reference data for conditions ranging from the triple point to the critical point. It is demonstrated that the use of ab initio potentials enables systematic improvements to the accuracy of predictions via the addition of theoretically based terms. The contribution of three-body interactions is accounted for using the Axilrod-Teller-Muto plus other multipole contributions and the effective Marcelli-Wang-Sadus potentials. The results indicate that the predictive ability of recent interatomic potentials, obtained from quantum chemical calculations, is comparable to that of accurate empirical models. It is demonstrated that the Marcelli-Wang-Sadus potential can be used in combination with accurate two-body ab initio models for the computationally inexpensive and accurate estimation of vapor-liquid phase equilibria. read less NOT USED (high confidence) M. Chrysos, “Dirac bubble potential for He-He and inadequacies in the continuum: Comparing an analytic model with elastic collision experiments.,” The Journal of chemical physics. 2017. link Times cited: 3 Abstract: We focus on the long-pending issue of the inadequacy of the … read moreAbstract: We focus on the long-pending issue of the inadequacy of the Dirac bubble potential model in the description of He-He interactions in the continuum [L. L. Lohr and S. M. Blinder, Int. J. Quantum Chem. 53, 413 (1995)]. We attribute this failure to the lack of a potential wall to mimic the onset of the repulsive interaction at close range separations. This observation offers the explanation to why this excessively simple model proves incapable of quantitatively reproducing previous experimental findings of glory scattering in He-He, although being notorious for its capability of reproducing several distinctive features of the atomic and isotopic helium dimers and trimers [L. L. Lohr and S. M. Blinder, Int. J. Quantum Chem. 90, 419 (2002)]. Here, we show that an infinitely high, energy-dependent potential wall of properly calculated thickness rc(E) taken as a supplement to the Dirac bubble potential suffices for agreement with variable-energy elastic collision cross section experiments for 4He-4He, 3He-4He, and 3He-3He [R. Feltgen et al., J. Chem. Phys. 76, 2360 (1982)]. In the very low energy regime, consistency is found between the Dirac bubble potential (to which our extended model is shown to reduce) and cold collision experiments [J. C. Mester et al., Phys. Rev. Lett. 71, 1343 (1993)]; this consistency, which in this regime lends credence to the Dirac bubble potential, was never noticed by its authors. The revised model being still analytic is of high didactical value while expected to increase in predictive power relative to other appraisals. read less NOT USED (high confidence) B. Jäger, R. Hellmann, E. Bich, and E. Vogel, “State-of-the-art ab initio potential energy curve for the krypton atom pair and thermophysical properties of dilute krypton gas.,” The Journal of chemical physics. 2016. link Times cited: 84 Abstract: A new reference krypton-krypton interatomic potential energy… read moreAbstract: A new reference krypton-krypton interatomic potential energy curve was developed by means of quantum-chemical ab initio calculations for 36 interatomic separations. Highly accurate values for the interaction energies at the complete basis set limit were obtained using the coupled-cluster method with single, double, and perturbative triple excitations as well as t-aug-cc-pV5Z and t-aug-cc-pV6Z basis sets including mid-bond functions, with the 6Z basis set being newly constructed for this study. Higher orders of coupled-cluster terms were considered in a successive scheme up to full quadruple excitations. Core-core and core-valence correlation effects were included. Furthermore, relativistic effects were studied not only at a scalar relativistic level using second-order direct perturbation theory, but also utilizing full four-component and Gaunt-effect computations. An analytical pair potential function was fitted to the interaction energies, which is characterized by a depth of 200.88 K with an estimated standard uncertainty of 0.51 K. Thermophysical properties of low-density krypton were calculated for temperatures up to 5000 K. Second and third virial coefficients were obtained from statistical thermodynamics. Viscosity and thermal conductivity as well as the self-diffusion coefficient were computed using the kinetic theory of gases. The theoretical results are compared with experimental data and with results for other pair potential functions from the literature, especially with those calculated from the recently developed ab initio potential of Waldrop et al. [J. Chem. Phys. 142, 204307 (2015)]. Highly accurate experimental viscosity data indicate that both the present ab initio pair potential and the one of Waldrop et al. can be regarded as reference potentials, even though the quantum-chemical methods and basis sets differ. However, the uncertainties of the present potential and of the derived properties are estimated to be considerably lower. read less NOT USED (high confidence) L. Viehland, R. Johnsen, B. R. Gray, and T. G. Wright, “Transport coefficients of He(+) ions in helium.,” The Journal of chemical physics. 2016. link Times cited: 10 Abstract: This paper demonstrates that the transport coefficients of (… read moreAbstract: This paper demonstrates that the transport coefficients of (4)He(+) in (4)He can be calculated over wide ranges of E/N, the ratio of the electrostatic field strength to the gas number density, with the same level of precision as can be obtained experimentally if sufficiently accurate potential energy curves are available for the X(2)Σu (+) and A(2)Σg (+) states and one takes into account resonant charge transfer. We start by computing new potential energy curves for these states and testing their accuracy by calculating spectroscopic values for the separate states. It is established that the potentials obtained by extrapolation of results from d-aug-cc-pVXZ (X = 6, 7) basis sets using the CASSCF+MRCISD approach are each in exceptionally close agreement with the best potentials available and with experiment. The potentials are then used in a new computer program to determine the semi-classical phase shifts and the transport cross sections, and from these the gaseous ion transport coefficients are determined. In addition, new experimental values are reported for the mobilities of (4)He(+) in (4)He at 298.7 K, as a function of E/N, where careful consideration is given to minimizing various sources of uncertainty. Comparison with previously measured values establishes that only one set of previous data is reliable. Finally, the experimental and theoretical ion transport coefficients are shown to be in very good to excellent agreement, once corrections are applied to account for quantum-mechanical effects. read less NOT USED (high confidence) L. Shirkov and J. Makarewicz, “Does DFT-SAPT method provide spectroscopic accuracy?,” The Journal of chemical physics. 2015. link Times cited: 11 Abstract: Ground state potential energy curves for homonuclear and het… read moreAbstract: Ground state potential energy curves for homonuclear and heteronuclear dimers consisting of noble gas atoms from He to Kr were calculated within the symmetry adapted perturbation theory based on the density functional theory (DFT-SAPT). These potentials together with spectroscopic data derived from them were compared to previous high-precision coupled cluster with singles and doubles including the connected triples theory calculations (or better if available) as well as to experimental data used as the benchmark. The impact of midbond functions on DFT-SAPT results was tested to study the convergence of the interaction energies. It was shown that, for most of the complexes, DFT-SAPT potential calculated at the complete basis set (CBS) limit is lower than the corresponding benchmark potential in the region near its minimum and hence, spectroscopic accuracy cannot be achieved. The influence of the residual term δ(HF) on the interaction energy was also studied. As a result, we have found that this term improves the agreement with the benchmark in the repulsive region for the dimers considered, but leads to even larger overestimation of potential depth De. Although the standard hybrid exchange-correlation (xc) functionals with asymptotic correction within the second order DFT-SAPT do not provide the spectroscopic accuracy at the CBS limit, it is possible to adjust empirically basis sets yielding highly accurate results. read less NOT USED (high confidence) A. Becker, W. Lorenzen, J. Fortney, N. Nettelmann, M. Schöttler, and R. Redmer, “AB INITIO EQUATIONS OF STATE FOR HYDROGEN (H-REOS.3) AND HELIUM (He-REOS.3) AND THEIR IMPLICATIONS FOR THE INTERIOR OF BROWN DWARFS,” The Astrophysical Journal Supplement Series. 2014. link Times cited: 129 Abstract: We present new equations of state (EOSs) for hydrogen and he… read moreAbstract: We present new equations of state (EOSs) for hydrogen and helium covering a wide range of temperatures from 60 K to 107 K and densities from 10−10 g cm−3 to 103 g cm−3. They include an extended set of ab initio EOS data for the strongly correlated quantum regime with an accurate connection to data derived from other approaches for the neighboring regions. We compare linear mixing isotherms based on our EOS tables with available real mixture data. A first important astrophysical application of this new EOS data is the calculation of interior models for Jupiter and comparison with recent results. Second, mass–radius relations are calculated for Brown Dwarfs (BDs) which we compare with predictions derived from the widely used EOS of Saumon, Chabrier, and van Horn. Furthermore, we calculate interior models for typical BDs with different masses, namely, Corot-3b, Gliese-229b, and Corot-15b, and the giant planet KOI-889b. The predictions for the central pressures and densities differ by up to 10% dependent on the EOS used. Our EOS tables are made available in the supplemental material of this paper. read less NOT USED (high confidence) F. Sharipov, “Gaseous mixtures in vacuum systems and microfluidics,” Journal of Vacuum Science and Technology. 2013. link Times cited: 33 Abstract: In vacuum technology, one deals with gaseous mixtures more f… read moreAbstract: In vacuum technology, one deals with gaseous mixtures more frequently than with a single gas, but the information about transport phenomena in mixtures published in the open literature is very poor. Moreover, methods to model mixture flows are more complicated than those for single gas. The aim of this work is to review general approaches to modeling mass, heat, and momentum transfer through gaseous mixtures over the whole range of gas rarefaction. This review is written in an easy, accessible manner avoiding hard mathematical derivations, though an extensive list of references is provided for readers wishing to find more details about the field. Results for some classical problems such as velocity slip and temperature jump coefficients, Poiseuille flow, Couette flow, and heat transfer for gaseous mixtures are presented in graphical form. A comparison of these results with those corresponding to a single gas is presented, which shows the peculiarities of the transport phenomena in mixtures and gives us an... read less NOT USED (high confidence) B. Song, X. Wang, and Z. Liu, “Thermal Conductivity of Pure Noble Gases at Low Density from Ab Initio Prandtl Number,” International Journal of Thermophysics. 2013. link Times cited: 2 NOT USED (high confidence) B. Jäger, “Thermodynamic Properties of Gaseous Argon from the Ab Initio Virial Equation of State,” Zeitschrift für Physikalische Chemie. 2013. link Times cited: 12 Abstract: A previously developed ab initio virial equation of state fo… read moreAbstract: A previously developed ab initio virial equation of state for argon (B. Jäger, R. Hellmann, E. Bich, E. Vogel, J. Chem. Phys. 135 (2011) 084308) was applied to calculate related thermophysical properties for the gaseous and supercritical region. Virial coefficients up to B7 were included considering also nonadditive three-body interactions and quantum corrections (for B2, B3, and B4). The results for the isothermal compressibility, the thermal expansivity, the isochoric and isobaric heat capacity, and for the speed of sound were compared with experimental data and with values obtained from a highly accurate empirical equation of state. It was generally found that the theoretical predictions are in very good agreement with the reference data except for the near-critical region and for higher densities. Hence, the theoretically calculated data can be useful for the improvement of equations of state, particularly for toxic or corrosive substances and for thermodynamic conditions, where experiments are difficult to perform (e.g. at high temperatures). The speed of sound was found to be the most suitable property to evaluate the quality of the underlying interaction potentials. read less NOT USED (high confidence) R. Hellmann, “Ab initio potential energy surface for the nitrogen molecule pair and thermophysical properties of nitrogen gas,” Molecular Physics. 2013. link Times cited: 86 Abstract: A four-dimensional potential energy hypersurface (PES) for t… read moreAbstract: A four-dimensional potential energy hypersurface (PES) for the interaction of two rigid nitrogen molecules was determined from high-level quantum-chemical ab initio computations. A total of 408 points for 26 distinct angular configurations were calculated utilizing the counterpoise-corrected supermolecular approach at the CCSD(T) level of theory and basis sets up to aug-cc-pV5Z supplemented with bond functions. The calculated interaction energies were extrapolated to the complete basis set limit and complemented by corrections for core–core and core–valence correlations, relativistic effects and higher coupled-cluster levels up to CCSDT(Q). An analytical site–site potential function with five sites per nitrogen molecule was fitted to the interaction energies. The PES was validated by computing second and third pressure virial coefficients as well as shear viscosity and thermal conductivity in the dilute-gas limit. An improved PES was obtained by scaling the CCSDT(Q) corrections for all 408 points by a constant factor, leading to quantitative agreement with the most accurate experimental values of the second virial coefficient over a wide temperature range. The comparison with the best experimental data for shear viscosity shows that the values computed with the improved PES are too low by about 0.3% between 300 and 700 K. For thermal conductivity large systematic deviations are found above 500 K between the calculated values and most of the experimental data. read less NOT USED (high confidence) R. F. Berg and W. Burton, “Noble gas viscosities at 25 °C,” Molecular Physics. 2013. link Times cited: 17 Abstract: Near 25 °C, ab initio calculations of the zero-density visco… read moreAbstract: Near 25 °C, ab initio calculations of the zero-density viscosity of helium gas η He have an uncertainty of approximately 0.001%, which is 1/40th of the uncertainty of the best measurements. The uncertainties of the published calculations for neon and argon are probably much larger. This paper presents new measurements of the viscosities of neon, argon, and krypton at 25 °C made with a capillary viscometer that was calibrated with helium. The resulting viscosity ratios are η Ne/η He = 1.59836 ± 0.00037, η Ar/η He = 1.13763 ± 0.00030, and η Kr/η He = 1.27520 ± 0.00040. The argon ratio agrees with a recent, unpublished calculation to within the combined uncertainty (measurement plus calculation) of 0.032%. The neon ratio is smaller than the calculated value by 0.13%. read less NOT USED (high confidence) M. El-Kader, “Thermophysical properties and collision-induced light scattering as a probe for gaseous helium interatomic potentials,” Molecular Physics. 2013. link Times cited: 2 Abstract: Isotropic and anisotropic collision-induced light scattering… read moreAbstract: Isotropic and anisotropic collision-induced light scattering spectra of helium gas at room temperature 294.5 K and at 99.6 K with the second pressure virial coefficients, second acoustic virial coefficients, viscosity and thermal conductivity have been used for deriving the empirical models of the pair-polarizability trace and anisotropy and the interaction potential. Theoretical zeroth and second moments of the binary spectra using various models for the pair-polarizabilities and interatomic potential are compared with the experimental values performed by Le Duff's group. In addition, third pressure virial coefficients, isotopic thermal factors, self diffusion coefficients, second virial dielectric constants and second Kerr coefficients calculated for these models are compared with experimental ones. The results show that these models are the most accurate models reported to date for this system. read less NOT USED (high confidence) W. Cencek, M. Przybytek, J. Komasa, J. Mehl, B. Jeziorski, and K. Szalewicz, “Effects of adiabatic, relativistic, and quantum electrodynamics interactions on the pair potential and thermophysical properties of helium.,” The Journal of chemical physics. 2012. link Times cited: 222 Abstract: The adiabatic, relativistic, and quantum electrodynamics (QE… read moreAbstract: The adiabatic, relativistic, and quantum electrodynamics (QED) contributions to the pair potential of helium were computed, fitted separately, and applied, together with the nonrelativistic Born-Oppenheimer (BO) potential, in calculations of thermophysical properties of helium and of the properties of the helium dimer. An analysis of the convergence patterns of the calculations with increasing basis set sizes allowed us to estimate the uncertainties of the total interaction energy to be below 50 ppm for interatomic separations R smaller than 4 bohrs and for the distance R = 5.6 bohrs. For other separations, the relative uncertainties are up to an order of magnitude larger (and obviously still larger near R = 4.8 bohrs where the potential crosses zero) and are dominated by the uncertainties of the nonrelativistic BO component. These estimates also include the contributions from the neglected relativistic and QED terms proportional to the fourth and higher powers of the fine-structure constant α. To obtain such high accuracy, it was necessary to employ explicitly correlated Gaussian expansions containing up to 2400 terms for smaller R (all R in the case of a QED component) and optimized orbital bases up to the cardinal number X = 7 for larger R. Near-exact asymptotic constants were used to describe the large-R behavior of all components. The fitted potential, exhibiting the minimum of -10.996 ± 0.004 K at R = 5.608 0 ± 0.000 1 bohr, was used to determine properties of the very weakly bound (4)He(2) dimer and thermophysical properties of gaseous helium. It is shown that the Casimir-Polder retardation effect, increasing the dimer size by about 2 Å relative to the nonrelativistic BO value, is almost completely accounted for by the inclusion of the Breit-interaction and the Araki-Sucher contributions to the potential, of the order α(2) and α(3), respectively. The remaining retardation effect, of the order of α(4) and higher, is practically negligible for the bound state, but is important for the thermophysical properties of helium. Such properties computed from our potential have uncertainties that are generally significantly smaller (sometimes by nearly two orders of magnitude) than those of the most accurate measurements and can be used to establish new metrology standards based on properties of low-density helium. read less NOT USED (high confidence) E. Vogel, “Towards Reference Viscosities of Carbon Monoxide and Nitrogen at Low Density Using Measurements between 290K and 680K as well as Theoretically Calculated Viscosities,” International Journal of Thermophysics. 2012. link Times cited: 24 NOT USED (high confidence) W. Cencek, J. Komasa, and K. Szalewicz, “Collision-induced dipole polarizability of helium dimer from explicitly correlated calculations.,” The Journal of chemical physics. 2011. link Times cited: 34 Abstract: Large expansions in basis sets of explicitly correlated Gaus… read moreAbstract: Large expansions in basis sets of explicitly correlated Gaussian functions and the variation-perturbation technique were used to calculate the static dipole polarizability of the helium dimer at 16 different internuclear separations from 1.0 to 9.0 bohrs. The convergence towards the complete basis set limit was analyzed in order to estimate uncertainties of all the calculated values. The results are significantly more accurate than literature data. Asymptotically correct analytic fits for the trace and anisotropy of collision-induced polarizability were obtained. read less NOT USED (high confidence) G. Garberoglio and A. Harvey, “Path-integral calculation of the third virial coefficient of quantum gases at low temperatures.,” The Journal of chemical physics. 2011. link Times cited: 34 Abstract: We derive path-integral expressions for the second and third… read moreAbstract: We derive path-integral expressions for the second and third virial coefficients of monatomic quantum gases. Unlike previous work that considered only Boltzmann statistics, we include exchange effects (Bose-Einstein or Fermi-Dirac statistics). We use state-of-the-art pair and three-body potentials to calculate the third virial coefficient of (3)He and (4)He in the temperature range 2.6-24.5561 K. We obtain uncertainties smaller than those of the limited experimental data. Inclusion of exchange effects is necessary to obtain accurate results below about 7 K. read less NOT USED (high confidence) E. Vogel, “Reference Viscosity of Argon at Low Density in the Temperature Range from 290 K to 680 K,” International Journal of Thermophysics. 2010. link Times cited: 35 NOT USED (high confidence) C. Gaiser and B. Fellmuth, “Helium virial coefficients—a comparison between new highly accurate theoretical and experimental data,” Metrologia. 2009. link Times cited: 24 Abstract: Critical tests of the accuracy of ab initio theoretical valu… read moreAbstract: Critical tests of the accuracy of ab initio theoretical values of the helium virial coefficients have been made based on experiments with a new dielectric-constant gas thermometry (DCGT) setup established at PTB. As the main starting point, most accurate experimental results for the thermodynamic temperature and the dielectric polarizability of 3He and 4He have been deduced recently. This paper now concentrates on the results for the two- and three-particle interaction described by the second and third density virial coefficients of helium. A comparison between experimental DCGT results and new highly accurate theoretical ab initio results shows an impressive agreement. The experimental uncertainties have been estimated via Monte-Carlo simulations and are comparable to the uncertainty of the latest theory. read less NOT USED (high confidence) W. Cencek, K. Patkowski, and K. Szalewicz, “Full-configuration-interaction calculation of three-body nonadditive contribution to helium interaction potential.,” The Journal of chemical physics. 2009. link Times cited: 43 Abstract: The three-body nonadditive interaction energy between helium… read moreAbstract: The three-body nonadditive interaction energy between helium atoms was calculated at 253 trimer configurations using the full-configuration-interaction (FCI) method. The analytic potential fitted to these energies is the best current representation of the three-body nonadditive interactions between helium atoms. At the equilateral triangle configuration with R=5.6 bohr, near the minimum of the total potential, the nonadditive three-body energy calculated at the FCI level amounts to -88.5 mK, compared to -98.5 mK at the coupled cluster with single, double, and noniterative triple excitations [CCSD(T)] level. The uncertainty of the former result resulting from basis set incompleteness is estimated to be 1.5 mK. The relative uncertainty of our present complete three-body fit, including the uncertainties resulting from the fitting procedure, is estimated at 2%, a fivefold improvement over the previous best potential. Overall, the FCI contribution beyond CCSD(T) is rather important, being of the same order of magnitude as the uncertainty of the sum of two-body interactions. The inclusion of this contribution makes uncertainties of the total trimer interaction energies dominated by the uncertainties of the two-body component. read less NOT USED (high confidence) K. Patkowski et al., “Potential energy surface for interactions between two hydrogen molecules.,” The Journal of chemical physics. 2008. link Times cited: 116 Abstract: Nonrelativistic clamped-nuclei energies of interaction betwe… read moreAbstract: Nonrelativistic clamped-nuclei energies of interaction between two ground-state hydrogen molecules with intramolecular distances fixed at their average value in the lowest rovibrational state have been computed. The calculations applied the supermolecular coupled-cluster method with single, double, and noniterative triple excitations [CCSD(T)] and very large orbital basis sets-up to augmented quintuple zeta size supplemented with bond functions. The same basis sets were used in symmetry-adapted perturbation theory calculations performed mainly for larger separations to provide an independent check of the supermolecular approach. The contributions beyond CCSD(T) were computed using the full configuration interaction method and basis sets up to augmented triple zeta plus midbond size. All the calculations were followed by extrapolations to complete basis set limits. For two representative points, calculations were also performed using basis sets with the cardinal number increased by one or two. For the same two points, we have also solved the Schrodinger equation directly using four-electron explicitly correlated Gaussian (ECG) functions. These additional calculations allowed us to estimate the uncertainty in the interaction energies used to fit the potential to be about 0.15 K or 0.3% at the minimum of the potential well. This accuracy is about an order of magnitude better than that achieved by earlier potentials for this system. For a near-minimum T-shaped configuration with the center-of-mass distance R=6.4 bohrs, the ECG calculations give the interaction energy of -56.91+/-0.06 K, whereas the orbital calculations in the basis set used for all the points give -56.96+/-0.16 K. The computed points were fitted by an analytic four-dimensional potential function. The uncertainties in the fit relative to the ab initio energies are almost always smaller than the estimated uncertainty in the latter energies. The global minimum of the fit is -57.12 K for the T-shaped configuration at R=6.34 bohrs. The fit was applied to compute the second virial coefficient using a path-integral Monte Carlo approach. The achieved agreement with experiment is substantially better than in any previous work. read less NOT USED (high confidence) B. Jäger, R. Hellmann, E. Bich, and E. Vogel, “Ab initio pair potential energy curve for the argon atom pair and thermophysical properties of the dilute argon gas. I. Argon–argon interatomic potential and rovibrational spectra,” Molecular Physics. 2008. link Times cited: 103 Abstract: An argon–argon interatomic potential energy curve was derive… read moreAbstract: An argon–argon interatomic potential energy curve was derived from quantum-mechanical ab initio calculations using basis sets of up to d-aug-cc-pV(6+d)Z quality supplemented with bond functions and ab initio methods up to CCSDT(Q). In addition, corrections for relativistic effects were determined. An analytical potential function was fitted to the ab initio values and utilised to compute the rovibrational spectrum. The quality of the interatomic potential function was tested by comparison of the calculated spectrum with experimental ones and those derived from other potentials of the literature. In a following paper the new interatomic potential is used to determine selected thermophysical properties of argon by means of quantum-statistical mechanics and the corresponding kinetic theory considering two-body and three-body interactions. read less NOT USED (high confidence) E. Vogel, B. Jäger, R. Hellmann, and E. Bich, “Ab initio pair potential energy curve for the argon atom pair and thermophysical properties for the dilute argon gas. II. Thermophysical properties for low-density argon,” Molecular Physics. 2008. link Times cited: 126 Abstract: A recent argon–argon interatomic potential energy curve dete… read moreAbstract: A recent argon–argon interatomic potential energy curve determined from quantum-mechanical ab initio calculations and described with an analytical representation [B. Jäger, R. Hellmann, E. Bich, and E. Vogel, Mol. Phys. 107, 2181 (2009); 108, 105 (2010)] was used to calculate the most important thermophysical properties of argon governed by two-body interactions. Second pressure, acoustic, and dielectric virial coefficients as well as viscosity and thermal conductivity in the limit of zero density were computed for natural argon from 83 to 10,000 K. The calculated values for the different thermophysical properties are compared with available experimental data and values computed for other argon–argon potentials. This extensive analysis shows that the proposed potential is superior to all previous ones and that the calculated thermophysical property values are accurate enough to be applied as standard values for the complete temperature range of the calculations. read less NOT USED (high confidence) R. J. Roy and A. Pashov, “betaFIT: A computer program to fit pointwise potentials to selected analytic functions,” Journal of Quantitative Spectroscopy & Radiative Transfer. 2017. link Times cited: 29 NOT USED (definite) G. Garberoglio and A. Harvey, “First-Principles Calculation of the Third Virial Coefficient of Helium,” Journal of Research of the National Institute of Standards and Technology. 2009. link Times cited: 41 Abstract: Knowledge of the pair and three-body potential-energy surfac… read moreAbstract: Knowledge of the pair and three-body potential-energy surfaces of helium is now sufficient to allow calculation of the third density virial coefficient, C(T), with significantly smaller uncertainty than that of existing experimental data. In this work, we employ the best available pair and three-body potentials for helium and calculate C(T) with path-integral Monte Carlo (PIMC) calculations supplemented by semiclassical calculations. The values of C(T) presented extend from 24.5561 K to 10 000 K. In the important metrological range of temperatures near 273.16 K, our uncertainties are smaller than the best experimental results by approximately an order of magnitude, and the reduction in uncertainty at other temperatures is at least as great. For convenience in calculation of C(T) and its derivatives, a simple correlating equation is presented. read less |
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