LAMMPS BOP potential for the Cd-Te system developed by Ward et al. (2012) v001

Donald K. Ward; Xiaowang Zhou; Bryan M. Wong; F. P. Doty; Jonathan A. Zimmerman

doi:10.25950/5c67ce36

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Sim_LAMMPS_BOP_WardZhouWong_2012_CdTe__SM_509819366101_001

Interatomic potential for Cadmium (Cd), Tellurium (Te).
Use this Potential

Title A single sentence description.	LAMMPS BOP potential for the Cd-Te system developed by Ward et al. (2012) v001
Description	CdTe and Cd1−xZnxTe are the leading semiconductor compounds for both photovoltaic and radiation detection applications. The performance of these materials is sensitive to the presence of atomic-scale defects in the structures. To enable accurate studies of these defects using modern atomistic simulation technologies, we have developed a high-fidelity analytical bond-order potential for the CdTe system. This potential incorporates primary (σ) and secondary (π) bonding and the valence dependence of the heteroatom interactions. The functional forms of the potential are directly derived from quantum-mechanical tight-binding theory under the condition that the first two and first four levels of the expanded Green's function for the σ- and π-bond orders, respectively, are retained. The potential parameters are optimized using iteration cycles that include first-fitting properties of a variety of elemental and compound configurations (with coordination varying from 1 to 12) including small clusters, bulk lattices, defects, and surfaces, and then checking crystalline growth through vapor deposition simulations. It is demonstrated that this CdTe bond-order potential gives structural and property trends close to those seen in experiments and quantum-mechanical calculations and provides a good description of melting temperature, defect characteristics, and surface reconstructions of the CdTe compound. Most importantly, this potential captures the crystalline growth of the ground-state structures for Cd, Te, and CdTe phases in vapor deposition simulations. HISTORY: Changes in version 001: * Parameter file formatted for compatibility with recent LAMMPS versions * Ghost atom communication cutoff increased from 14.70 Angstroms to 14.71 Angstroms to account for new, more strict comparison with max bop cutoff done in recent LAMMPS versions
Species The supported atomic species.	Cd, Te
Disclaimer A statement of applicability provided by the contributor, informing users of the intended use of this KIM Item.	None
Content Origin	LAMMPS package 30-Jul-2021

Contributor	Ronald E. Miller
Maintainer	Ronald E. Miller
Developer	Donald K. Ward Xiaowang Zhou Bryan M. Wong F. P. Doty Jonathan A. Zimmerman
Published on KIM	2021
How to Cite	This Simulator Model originally published in [1] is archived in OpenKIM [2-4]. [1] Ward DK, Zhou XW, Wong BM, Doty FP, Zimmerman JA. Analytical bond-order potential for the cadmium telluride binary system. Phys Rev B [Internet]. 2012Mar;85(11):115206. Available from: https://link.aps.org/doi/10.1103/PhysRevB.85.115206 doi:10.1103/PhysRevB.85.115206 — (Primary Source) A primary source is a reference directly related to the item documenting its development, as opposed to other sources that are provided as background information. [2] Ward DK, Zhou X, Wong BM, Doty FP, Zimmerman JA. LAMMPS BOP potential for the Cd-Te system developed by Ward et al. (2012) v001. OpenKIM; 2021. doi:10.25950/5c67ce36 [3] Tadmor EB, Elliott RS, Sethna JP, Miller RE, Becker CA. The potential of atomistic simulations and the Knowledgebase of Interatomic Models. JOM. 2011;63(7):17. doi:10.1007/s11837-011-0102-6 [4] Elliott RS, Tadmor EB. Knowledgebase of Interatomic Models (KIM) Application Programming Interface (API). OpenKIM; 2011. doi:10.25950/ff8f563a Click here to download the above citation in BibTeX format.
Citations This panel presents information regarding the papers that have cited the interatomic potential (IP) whose page you are on. The OpenKIM machine learning based Deep Citation framework is used to determine whether the citing article actually used the IP in computations (denoted by "USED") or only provides it as a background citation (denoted by "NOT USED"). For more details on Deep Citation and how to work with this panel, click the documentation link at the top of the panel. The word cloud to the right is generated from the abstracts of IP principle source(s) (given below in "How to Cite") and the citing articles that were determined to have used the IP in order to provide users with a quick sense of the types of physical phenomena to which this IP is applied. The bar chart shows the number of articles that cited the IP per year. Each bar is divided into green (articles that USED the IP) and blue (articles that did NOT USE the IP). Users are encouraged to correct Deep Citation errors in determination by clicking the speech icon next to a citing article and providing updated information. This will be integrated into the next Deep Citation learning cycle, which occurs on a regular basis. OpenKIM acknowledges the support of the Allen Institute for AI through the Semantic Scholar project for providing citation information and full text of articles when available, which are used to train the Deep Citation ML algorithm.	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. 66 Citations (32 used) Show Model Used Show All Help us to determine which of the papers that cite this potential actually used it to perform calculations. If you know, click the . M. Yu and S. Kenny, “Using atomistic simulations to model cadmium telluride thin film growth,” Journal of Physics: Condensed Matter. 2016. link Times cited: 3 Abstract: Cadmium telluride (CdTe) is an excellent material for low-co… read more Abstract: Cadmium telluride (CdTe) is an excellent material for low-cost, high efficiency thin film solar cells. It is important to conduct research on how defects are formed during the growth process, since defects lower the efficiency of solar cells. In this work we use computer simulation to predict the growth of a sputter deposited CdTe thin film. On-the-fly kinetic Monte Carlo technique is used to simulate the CdTe thin film growth on the (1 1 1) surfaces. The results show that on the (1 1 1) surfaces the growth mechanisms on surfaces which are terminated by Cd or Te are quite different, regardless of the deposition energy (0.1∼10 ?> eV). On the Te-terminated (1 1 1) surface the deposited clusters first form a single mixed species layer, then the Te atoms in the mixed layer moved up to form a new layer. Whilst on the Cd-terminated (1 1 1) surface the new Cd and Te layers are formed at the same time. Such differences are probably caused by stronger bonding between ad-atoms and surface atoms on the Te layer than on the Cd layer. read less M. Yu and S. Kenny, “The energetic impact of small CdxTey clusters on Cadmium Telluride,” Thin Solid Films. 2015. link Times cited: 4 P. Fan, S. Goel, X. Luo, and H. Upadhyaya, “Atomic-Scale Friction Studies on Single-Crystal Gallium Arsenide Using Atomic Force Microscope and Molecular Dynamics Simulation,” Nanomanufacturing and Metrology. 2021. link Times cited: 9 P. Fan, S. Goel, X. Luo, and H. Upadhyaya, “Atomic-Scale Friction Studies on Single-Crystal Gallium Arsenide Using Atomic Force Microscope and Molecular Dynamics Simulation,” Nanomanufacturing and Metrology. 2021. link Times cited: 0 I. Khatri and J. Amar, “Energy, temperature, and deposition angle dependence of Cd and Te2 deposited on CdTe,” Thin Solid Films. 2020. link Times cited: 1 Y. Tan, Y.-J. Zhao, L. Luo, X.-B. Yang, and H. Xu, “Theoretical studies of geometry asymmetry in tellurium nanostructures: intrinsic dipole, charge separation, and semiconductor–metal transition,” RSC Advances. 2014. link Times cited: 2 Abstract: Bulk tellurium (Te) presents a threefold screw axis with hig… read more Abstract: Bulk tellurium (Te) presents a threefold screw axis with highly anisotropic chain structure, where every Te atom forms strong covalent bonds in the chain and much weaker bonds in the adjacent chains. The bonds in the adjacent chains are critical to the total energies of Te nanostructures since the nearest neighbors are always saturated. Confirmed by our model simulation and first-principles calculations, the nanobelts would be stabilized at the temperature of 600 K due to the entropy effect, though the hexagonal nanowires have the smallest surface-to-volume ratio. Attributed to the geometry asymmetry of the highly anisotropic chain, we showed that the difference of weaker bonds' distribution induces an intrinsic dipole, and thus a charge separation at the two ends of Te nanobelts. Interestingly, it further leads to a semiconductor–metal transition which is also verified by our first-principles calculations. Our finding provides a new mechanism of charge separation and semiconductor–metal transition, due to the unique asymmetry of geometry in Te nanostructures. read less S. Sarkar, S. Saha, S. Pal, and P. Sarkar, “Electronic structure and bandgap engineering of CdTe nanotubes and designing the CdTe nanotube–fullerene hybrid nanostructures for photovoltaic applications,” RSC Advances. 2014. link Times cited: 16 Abstract: The electronic structure of CdTe nanotube–fullerene nanocomp… read more Abstract: The electronic structure of CdTe nanotube–fullerene nanocomposites has been explored. Within this context, the structural and electronic properties of isolated 100 faceted CdTe nanotubes (NTs) with hexagonal cross-sections were first investigated using the self-consistent-charge density-functional tight-binding (SCC-DFTB) method. The possibility of band gap engineering of clean CdTe nanotubes is explored by varying either the size or wall thickness of the NTs. However, the efficient modification of the band gap can be attained by introducing the molecular states of fullerene into the band gap region of the CdTe NTs. The effects of the modulation of the band alignment through the variation in the wall thickness of the CdTe NTs on the electron injection rate from the NT to C60 in hybrid systems have been explored and we also found that the light harvesting efficiency of these nanohybrids can be maximized by increasing the concentration of the C60–thiol moieties. The position of the electronic energy levels offers information about the electronic structure of the hybrid systems such as whether it constructs type I or type II hetero-junctions, which bears key information for their application in photovoltaics. We also studied the electronic structure of CdTe–fullerene hybrid nanostructures with a series of fullerenes of different compositions. read less D. Peng et al., “The influence of lead on mechanical properties of BCC and FCC iron from a constructed bond-order potential,” The European Physical Journal Plus. 2023. link Times cited: 0 J. Y. Li, K. Luo, and Q. An, “Atomic structure, stability, and dissociation of dislocations in cadmium telluride,” International Journal of Plasticity. 2023. link Times cited: 4 P. Fan et al., “Oblique nanomachining of gallium arsenide explained using AFM experiments and MD simulations,” Journal of Manufacturing Processes. 2023. link Times cited: 0 Y. Li, Z. Zheng, A. Diaz, S. Phillpot, D. McDowell, and Y. Chen, “Resonant interaction between phonons and PbTe/PbSe (001) misfit dislocation networks,” Acta Materialia. 2022. link Times cited: 4 Z. Liang, Y. Jiang, X. Gong, and H. Gong, “Atomistic modelling of the immiscible Fe–Bi system from a constructed bond order potential,” Journal of Physics: Condensed Matter. 2021. link Times cited: 2 Abstract: An analytical bond-order potential (BOP) of Fe–Bi has been c… read more Abstract: An analytical bond-order potential (BOP) of Fe–Bi has been constructed and has been validated to have a better performance than the Fe–Bi potentials already published in the literature. Molecular dynamics simulations based on this BOP has been then conducted to investigate the ground-state properties of Bi, structural stability of the Fe–Bi binary system, and the effect of Bi on mechanical properties of BCC Fe. It is found that the present BOP could accurately predict the ground-state A7 structure of Bi and its structural parameters, and that a uniform amorphous structure of Fe100−x Bi x could be formed when Bi is located in the composition range of 26 ⩽ x < 70. In addition, simulations also reveal that the addition of a very small percentage of Bi would cause a considerable decrease of tensile strength and critical strain of BCC Fe upon uniaxial tensile loading. The obtained results are in nice agreement with similar experimental observations in the literature. read less F. Sen et al., “Computational design of passivants for CdTe grain boundaries,” Solar Energy Materials and Solar Cells. 2021. link Times cited: 3 X. Xu, W. Fan, B. Li, and J. Cao, “Influence of GaAs crystal anisotropy on deformation behavior and residual stress distribution of nanoscratching,” Applied Physics A. 2021. link Times cited: 4 P. Fan et al., “Molecular dynamics simulation of AFM tip-based hot scratching of nanocrystalline GaAs,” Materials Science in Semiconductor Processing. 2021. link Times cited: 11 N. Hew, D. Spagnoli, and L. Faraone, “Dislocation core energies of the 0° perfect, 60° perfect, 30° partial, and 90° partial dislocations in CdTe, HgTe, and ZnTe: A molecular statics and elasticity theory analysis,” Materials today communications. 2021. link Times cited: 3 P. Fan, S. Goel, X. Luo, Y. Yan, Y. Geng, and Y. Wang, “An atomistic investigation on the wear of diamond during atomic force microscope tip-based nanomachining of gallium arsenide,” Computational Materials Science. 2021. link Times cited: 11 B. Köylüoğlu, S. Alaei, and M. Kurban, “Molecular dynamics study on composition and temperature dependences of mechanical properties of CdTeSe nanowires under uniaxial stretching,” International Journal of Modern Physics B. 2019. link Times cited: 2 Abstract: In this study, a molecular dynamics (MD) study has been perf… read more Abstract: In this study, a molecular dynamics (MD) study has been performed on composition and temperature dependences of mechanical properties of CdTe1−xSex (x = 0.25, 0.50 and 0.75) nanowires with a diamet... read less G. Plummer and G. Tucker, “Bond-order potentials for theTi3AlC2andTi3SiC2MAX phases,” Physical Review B. 2019. link Times cited: 12 M. A. M. Munshi, S. Majumder, M. Motalab, and S. Saha, “Insights into the mechanical properties and fracture mechanism of Cadmium Telluride nanowire,” Materials Research Express. 2019. link Times cited: 19 Abstract: Semiconducting nanowires (NWs), key building blocks in nanot… read more Abstract: Semiconducting nanowires (NWs), key building blocks in nanotechnology with many potential applications, are stirring the attention of the scientific world because of their many unique properties. Cadmium telluride (CdTe) single crystal nanowires, with Zinc Blende (ZB) crystal configuration, have become the focus of interest nowadays due to its promising application in Opto-electro-mechanical nanodevices. However, due to the lack of complete insight into their mechanical deformation, it is necessary to thoroughly study the CdTe nanowires. In this study, molecular dynamics simulations have been used to investigate the mechanical behavior of CdTe nanowires (NWs) by varying size, temperature, crystal orientation, and strain rate under tension and compression. Results show that the fracture strength of the [111]-oriented CdTe NWs is always higher than that of the [110]-oriented CdTe NWs under tension whereas, in compression, the fracture strength of the [111]-oriented CdTe NWs is significantly lower than that of the [110]-oriented CdTe NWs. Moreover, upon applying the tensile load along NWs growth direction, the [111]-oriented CdTe NWs fail by creating void in [10-1] direction due to bond breaking in [1-21] direction regardless of temperature and NW size. Under compression, the [111]-oriented nanowires show buckling and plasticity. It has also been observed that size has a negligible effect on the tensile behavior but in compression, the behavior is size-dependent. Both tensile and compressive strengths show an inverse relation with temperature. Finally, the impact of strain rate on [111]-oriented CdTe NWs are also studied where higher fracture strengths and strains at higher strain rates have been found under both tension and compression. With increasing the strain rate, the number of voids is also increased in the NWs. This study will help to design CdTe NWs based devices efficiently by presenting an in-depth understanding of the failure behavior of the [111]-oriented CdTe NWs. read less Y. Shen et al., “Interface regulation and photoelectric performance of CdZnTe/AlN composite structure for UV photodetector,” Surface and Coatings Technology. 2019. link Times cited: 9 Z. Zhang et al., “Preparation and surface defect regulation of CdZnTe films based on GaN substrates,” Vacuum. 2018. link Times cited: 14 X. Qian, X. Gu, and R. Yang, “Thermal conductivity modeling of hybrid organic-inorganic crystals and superlattices,” Nano Energy. 2017. link Times cited: 31 P. Xiao, F. Ke, Y.-long Bai, and M. Zhou, “Deformation-induced blueshift in emission spectrum of CdTe quantum dot composites,” Composites Part B-engineering. 2017. link Times cited: 6 M. Kurban and S. Erkoç, “Mechanical properties of CdZnTe nanowires under uniaxial stretching and compression: A molecular dynamics simulation study,” Computational Materials Science. 2016. link Times cited: 14 X. W. Zhou, J. J. Chavez, and D. Zubia, “Molecular Dynamics Analysis of Nanostructures.” 2016. link Times cited: 0 C. Sun et al., “Atomic and electronic structure of Lomer dislocations at CdTe bicrystal interface,” Scientific Reports. 2016. link Times cited: 38 M. Kurban, O. B. Malcıoğlu, and S. Erkoç, “Structural and thermal properties of Cd–Zn–Te ternary nanoparticles: Molecular-dynamics simulations,” Chemical Physics. 2016. link Times cited: 22 A. Nassour, “First-principles calculations of structural properties and lattice dynamics in ZnSexTe1−x alloys,” Computational Materials Science. 2013. link Times cited: 1 X. W. Zhou, D. Ward, J. E. Martin, F. Swol, J. Cruz-Campa, and D. Zubia, “Stillinger-Weber potential for the II-VI elements Zn-Cd-Hg-S-Se-Te,” Physical Review B. 2013. link Times cited: 86 Abstract: X. W. Zhou,1,* D. K. Ward,2 J. E. Martin,3 F. B. van Swol,4 … read more Abstract: X. W. Zhou,1,* D. K. Ward,2 J. E. Martin,3 F. B. van Swol,4 J. L. Cruz-Campa,5 and D. Zubia6 1Mechanics of Materials Department, Sandia National Laboratories, Livermore, California 94550, USA 2Radiation and Nuclear Detection Materials and Analysis Department, Sandia National Laboratories, Livermore, California 94550, USA 3Nanoscale Sciences Department, Sandia National Laboratories, Albuquerque, New Mexico 87185, USA 4Computational Materials and Data Science Department, Sandia National Laboratories, Albuquerque, New Mexico 87185, USA 5MEMS Technologies Department, Sandia National Laboratories, Albuquerque, New Mexico 87185, USA 6Department of Electrical Engineering, University of Texas at El Paso, El Paso, Texas 79968, USA (Received 30 May 2013; published 9 August 2013; corrected 13 November 2013) read less J. M. Polfus, T. S. Bjørheim, T. Norby, and R. Haugsrud, “Nitrogen defects in wide band gap oxides: defect equilibria and electronic structure from first principles calculations.,” Physical chemistry chemical physics : PCCP. 2012. link Times cited: 17 Abstract: The nitrogen related defect chemistry and electronic structu… read more Abstract: The nitrogen related defect chemistry and electronic structure of wide band gap oxides are investigated by density functional theory defect calculations of N(O)(q), NH(O)(×), and (NH2)(O)(·) as well as V(O)(··) and OH(O)(·) in MgO, CaO, SrO, Al(2)O(3), In(2)O(3), Sc(2)O(3), Y(2)O(3), La(2)O(3), TiO(2), SnO(2), ZrO(2), BaZrO(3), and SrZrO(3). The N(O)(q) acceptor level is found to be deep and the binding energy of NH(O)(×) with respect to N(O)' and (OH(O)(·) is found to be significantly negative, i.e. binding, in all of the investigated oxides. The defect structure of the oxides was found to be remarkably similar under reducing and nitriding conditions (1 bar N(2), 1 bar H(2) and 1 × 10(-7) bar H(2)O): NH(O)(×) predominates at low temperatures and [N(O)'] = 2[V(O)(··) predominates at higher temperatures (>900 K for most of the oxides). Furthermore, we evaluate how the defect structure is affected by non-equilibrium conditions such as doping and quenching. In terms of electronic structure, N(O)' is found to introduce isolated N-2p states within the band gap, while the N-2p states of NH(O)(×) are shifted towards, or overlap with the VBM. Finally, we assess the effect of nitrogen incorporation on the proton conducting properties of oxides and comment on their corrosion resistance in nitriding atmospheres in light of the calculated defect structures. read less X. W. Zhou, D. Ward, B. M. Wong, F. Doty, and J. Zimmerman, “Molecular Dynamics Studies of Dislocations in CdTe Crystals from a New Bond Order Potential,” The Journal of Physical Chemistry. C, Nanomaterials and Interfaces. 2012. link Times cited: 29 Abstract: Cd1-xZnxTe (CZT) crystals are the leading semiconductors for… read more Abstract: Cd1-xZnxTe (CZT) crystals are the leading semiconductors for radiation detection, but their application is limited by the high cost of detector-grade materials. High crystal costs primarily result from property nonuniformity that causes low manufacturing yield. Although tremendous efforts have been made in the past to reduce Te inclusions/precipitates in CZT, this has not resulted in an anticipated improvement in material property uniformity. Moreover, it is recognized that in addition to Te particles, dislocation cells can also cause electric field perturbations and the associated property nonuniformities. Further improvement of the material, therefore, requires that dislocations in CZT crystals be understood and controlled. Here, we use a recently developed CZT bond order potential to perform representative molecular dynamics simulations to study configurations, energies, and mobilities of 29 different types of possible dislocations in CdTe (i.e., x = 1) crystals. An efficient method to derive activation free energies and activation volumes of thermally activated dislocation motion will be explored. Our focus gives insight into understanding important dislocations in the material and gives guidance toward experimental efforts for improving dislocation network structures in CZT crystals. read less A. Thompson et al., “LAMMPS - A flexible simulation tool for particle-based materials modeling at the atomic, meso, and continuum scales,” Computer Physics Communications. 2021. link Times cited: 2377 X. Chen et al., “Machine learning enhanced empirical potentials for metals and alloys,” Comput. Phys. Commun. 2021. link Times cited: 5 X. W. Zhou, M. E. Foster, R. Jones, P. Yang, H. Fan, and F. Doty, “A modified Stillinger-Weber potential for TlBr and its polymorphic extension,” Journal of Materials Science Research. 2015. link Times cited: 6 Abstract: TlBr is promising for g- and x- radiation detection, but suf… read more Abstract: TlBr is promising for g- and x- radiation detection, but suffers from rapid performance degradation under the operating external electric fields. To enable molecular dynamics (MD) studies of this degradation, we have developed a Stillinger-Weber type of TlBr interatomic potential. During this process, we have also addressed two problems of wider interests. First, the conventional Stillinger-Weber potential format is only applicable for tetrahedral structures (e.g., diamond-cubic, zinc-blende, or wurtzite). Here we have modified the analytical functions of the Stillinger-Weber potential so that it can now be used for other crystal structures. Second, past modifications of interatomic potentials cannot always be applied by a broad community because any new analytical functions of the potential would require corresponding changes in the molecular dynamics codes. Here we have developed a polymorphic potential model that simultaneously incorporates Stillinger-Weber, Tersoff, embedded-atom method, and any variations (i.e., modified functions) of these potentials. We have implemented this polymorphic model in MD code LAMMPS, and demonstrated that our TlBr potential enables stable MD simulations under external electric fields. read less A. Kumar, P. Rawat, and P. Banerji, “Carrier transport phenomenon and thermoelectric properties in melt-grown tellurium doped n-type Bi0.88Sb0.12 alloy,” Materials Science and Engineering B-advanced Functional Solid-state Materials. 2014. link Times cited: 4 M. Korth, “Error estimates for (semi-)empirical dispersion terms and large biomacromolecules.,” Organic & biomolecular chemistry. 2013. link Times cited: 9 Abstract: The first-principles modeling of biomaterials has made treme… read more Abstract: The first-principles modeling of biomaterials has made tremendous advances over the last few years with the ongoing growth of computing power and impressive developments in the application of density functional theory (DFT) codes to large systems. One important step forward was the development of dispersion corrections for DFT methods, which account for the otherwise neglected dispersive van der Waals (vdW) interactions. Approaches at different levels of theory exist, with the most often used (semi-)empirical ones based on pair-wise interatomic C6R(-6) terms. Similar terms are now also used in connection with semiempirical QM (SQM) methods and density functional tight binding methods (SCC-DFTB). Their basic structure equals the attractive term in Lennard-Jones potentials, common to most force field approaches, but they usually use some type of cutoff function to make the mixing of the (long-range) dispersion term with the already existing (short-range) dispersion and exchange-repulsion effects from the electronic structure theory methods possible. All these dispersion approximations were found to perform accurately for smaller systems, but error estimates for larger systems are very rare and completely missing for really large biomolecules. We derive such estimates for the dispersion terms of DFT, SQM and MM methods using error statistics for smaller systems and dispersion contribution estimates for the PDBbind database of protein-ligand interactions. We find that dispersion terms will usually not be a limiting factor for reaching chemical accuracy, though some force fields and large ligand sizes are problematic. read less J. Cruz-Campa et al., “Record breaking solar cells : ZnxCd(1-x)Te graded bandgap nanoarrays.” 2012. link Times cited: 1 Abstract: CdTe is the leading material for thin-film solar cells due t… read more Abstract: CdTe is the leading material for thin-film solar cells due to ease of processing and reduced cost. However, low conversion efficiencies due to defects in the material are still a problem in these devices. We propose implementing micro and nano-enabled pseudomorphic growth of ZnCdTe to dramatically increase the efficiency of CdTe solar cells. Simulations predict that defect-free films are possible in graded ZnCdTe nanoislands below 90 nm as well as 24 % efficient solar cells with the use of ZnCdTe grading. Selective growth of CdTe showed single grains when the island sizes decreased below 300 nm. The simulation and experimental results demonstrate for the first time the ability to use nanopatterned substrates to enhance uniformity and efficiency in CdTe thin film solar cells. More than 20 reports, presentations, and papers were produced as part of this work and the results from this project enabled UTEP and Sandia to secure to grants. read less P. Sun, J. Hastings, D. Ishikawa, A. Baron, and G. Monaco, “Universal Two-Component Dynamics in Supercritical Fluids,” The Journal of Physical Chemistry. B. 2021. link Times cited: 0 Abstract: Despite the technological importance of supercritical fluids… read more Abstract: Despite the technological importance of supercritical fluids, controversy remains about the details of their microscopic dynamics. In this work, we study four supercritical fluid systems—water, Si, Te, and Lennard-Jones fluid—via classical molecular dynamics simulations. A universal two-component behavior is observed in the intermolecular dynamics of these systems, and the changing ratio between the two components leads to a crossover from liquidlike to gaslike dynamics, most rapidly around the Widom line. We find evidence to connect the liquidlike component dominating at lower temperatures with intermolecular bonding and the component prominent at higher temperatures with free-particle, gaslike dynamics. The ratio between the components can be used to describe important properties of the fluid, such as its self-diffusion coefficient, in the transition region. Our results provide an insight into the fundamental mechanism controlling the dynamics of supercritical fluids and highlight the role of spatiotemporally inhomogeneous dynamics even in thermodynamic states where no large-scale fluctuations exist in the fluid. read less P. Fan, F. Ding, X. Luo, Y. Yan, Y. Geng, and Y. Wang, “A Simulated Investigation of Ductile Response of GaAs in Single-Point Diamond Turning and Experimental Validation,” Nanomanufacturing and Metrology. 2020. link Times cited: 11 P. Hatton et al., “Inert gas bubble formation in magnetron sputtered thin-film CdTe solar cells,” Proceedings. Mathematical, Physical, and Engineering Sciences. 2020. link Times cited: 7 Abstract: Cadmium telluride (CdTe) solar cells are deposited in curren… read more Abstract: Cadmium telluride (CdTe) solar cells are deposited in current production using evaporation-based tech- niques. Fabricating CdTe solar cells using magnetron sputtering would have the advantage of being more cost-efficient. Here, we show that such deposition results in the incorporation of the magnetron working gas Ar, within the films. Post deposition processing with CdCl2 improves cell efficiency and during which stacking faults are removed. The Ar then accumulates into clusters leading to the creation of voids and blisters on the surface. Using molecular dynamics, the penetration threshold energies are determined for both Ar and Xe, with CdTe in both zinc-blende and wurtzite phases. These calculations show that more Ar than Xe can penetrate into the growing film with most penetration across the (111) surface. The mechanisms and energy barriers for interstitial Ar and Xe diffusion in zinc-blende are determined. Barriers are reduced near existing clusters, increasing the probability of capture-based cluster growth. Barriers in wurtzite are higher with non-Arrhenius behaviour observed. This provides an explanation for the increase in the size of voids observed after stacking fault removal. Blister exfoliation was also modelled, showing the formation of shallow craters with a raised rim. read less G. Stechmann, S. Zaefferer, and D. Raabe, “Molecular statics simulation of CdTe grain boundary structures and energetics using a bond-order potential,” Modelling and Simulation in Materials Science and Engineering. 2018. link Times cited: 2 Abstract: The structure and energetics of coincidence site lattice gra… read more Abstract: The structure and energetics of coincidence site lattice grain boundaries (GB) in CdTe are investigated by mean of molecular statics simulations, using the Cd–Zn–Te bond-order potential (second iteration) developed by Ward et al (2012 Phys. Rev. B 86 245203; 2013 J. Mol. Modelling 19 5469–77). The effects of misorientation (Σ value) and interface plane are treated separately, complying with the critical need for full five-parameter characterization of GB. In addition, stoichiometric shifts, occurring between the inner interfaces and their adjacent atomic layers, are also predicted, revealing the energetic preference of Te-rich boundaries, opening opportunities for crystallography-based intrinsic interface doping. Our results also suggest that the intuitive assumption that Σ3 boundaries with low-indexed planes are more energetically favorable is often unfounded, except for coherent twins developing on {111} boundary planes. Therefore, Σ5, 7 or 9 boundaries, with lower interface energy than that of twin boundaries lying on different facets, are frequently encountered. read less X. W. Zhou, R. Jones, and K. Chu, “Polymorphic improvement of Stillinger-Weber potential for InGaN,” Journal of Applied Physics. 2017. link Times cited: 4 Abstract: A Stillinger-Weber potential is computationally very efficie… read more Abstract: A Stillinger-Weber potential is computationally very efficient for molecular dynamics simulations. Despite its simple mathematical form, the Stillinger-Weber potential can be easily parameterized to ensure that crystal structures with tetrahedral bond angles (e.g., diamond-cubic, zinc-blende, and wurtzite) are stable and have the lowest energy. As a result, the Stillinger-Weber potential has been widely used to study a variety of semiconductor elements and alloys. When studying an A-B binary system, however, the Stillinger-Weber potential is associated with two major drawbacks. First, it significantly overestimates the elastic constants of elements A and B, limiting its use for systems involving both compounds and elements (e.g., an A/AB multilayer). Second, it prescribes equal energy for zinc-blende and wurtzite crystals, limiting its use for compounds with large stacking fault energies. Here, we utilize the polymorphic potential style recently implemented in LAMMPS to develop a modified Stillinger-Weber potential for InGaN that overcomes these two problems.A Stillinger-Weber potential is computationally very efficient for molecular dynamics simulations. Despite its simple mathematical form, the Stillinger-Weber potential can be easily parameterized to ensure that crystal structures with tetrahedral bond angles (e.g., diamond-cubic, zinc-blende, and wurtzite) are stable and have the lowest energy. As a result, the Stillinger-Weber potential has been widely used to study a variety of semiconductor elements and alloys. When studying an A-B binary system, however, the Stillinger-Weber potential is associated with two major drawbacks. First, it significantly overestimates the elastic constants of elements A and B, limiting its use for systems involving both compounds and elements (e.g., an A/AB multilayer). Second, it prescribes equal energy for zinc-blende and wurtzite crystals, limiting its use for compounds with large stacking fault energies. Here, we utilize the polymorphic potential style recently implemented in LAMMPS to develop a modified Stillinger-Weber... read less J. Kunc, P. Praus, E. Belas, V. Dvedivc, J. Pek’arek, and R. Grill, “Efficient Charge Collection in Coplanar-Grid Radiation Detectors,” Physical review applied. 2017. link Times cited: 1 Abstract: We have modeled laser-induced transient current waveforms in… read more Abstract: We have modeled laser-induced transient current waveforms in radiation coplanar grid detectors. Poisson's equation has been solved by finite element method and currents induced by photo-generated charge were obtained using Shockley-Ramo theorem. The spectral response on a radiation flux has been modeled by Monte-Carlo simulations. We show 10$\times$ improved spectral resolution of coplanar grid detector using differential signal sensing. We model the current waveform dependence on doping, depletion width, diffusion and detector shielding and their mutual dependence is discussed in terms of detector optimization. The numerical simulations are successfully compared to experimental data and further model simplifications are proposed. The space charge below electrodes and a non-homogeneous electric field on a coplanar grid anode are found to be the dominant contributions to laser-induced transient current waveforms. read less X. W. Zhou, D. Ward, and M. E. Foster, “An analytical bond-order potential for the aluminum copper binary system,” Journal of Alloys and Compounds. 2016. link Times cited: 38 X. W. Zhou, D. Ward, and M. E. Foster, “An analytical bond‐order potential for carbon,” Journal of Computational Chemistry. 2015. link Times cited: 38 Abstract: Carbon is the most widely studied material today because it … read more Abstract: Carbon is the most widely studied material today because it exhibits special properties not seen in any other materials when in nano dimensions such as nanotube and graphene. Reduction of material defects created during synthesis has become critical to realize the full potential of carbon structures. Molecular dynamics (MD) simulations, in principle, allow defect formation mechanisms to be studied with high fidelity, and can, therefore, help guide experiments for defect reduction. Such MD simulations must satisfy a set of stringent requirements. First, they must employ an interatomic potential formalism that is transferable to a variety of carbon structures. Second, the potential needs to be appropriately parameterized to capture the property trends of important carbon structures, in particular, diamond, graphite, graphene, and nanotubes. Most importantly, the potential must predict the crystalline growth of the correct phases during direct MD simulations of synthesis to achieve a predictive simulation of defect formation. Because an unlimited number of structures not included in the potential parameterization are encountered, the literature carbon potentials are often not sufficient for growth simulations. We have developed an analytical bond order potential for carbon, and have made it available through the public MD simulation package LAMMPS. We demonstrate that our potential reasonably captures the property trends of important carbon phases. Stringent MD simulations convincingly show that our potential accounts not only for the crystalline growth of graphene, graphite, and carbon nanotubes but also for the transformation of graphite to diamond at high pressure. © 2015 Wiley Periodicals, Inc. read less F. Sen et al., “Atomistic simulations of grain boundaries in CdTe,” 2015 IEEE 42nd Photovoltaic Specialist Conference (PVSC). 2015. link Times cited: 4 Abstract: An improvement in efficiencies of polycrystalline CdTe can p… read more Abstract: An improvement in efficiencies of polycrystalline CdTe can possibly be achieved by understanding the role of grain boundaries. Therefore, we systematically studied the atomic and electronic structures of various high angle grain boundaries including asymmetric tilt and twist grain boundaries using empirical potentials and density functional theory (DFT). The density of states analysis revealed that most grain boundaries lead to the formation of midgap states, which can drastically reduce the photovoltaic efficiency. The planar-averaged electrostatic potential analysis indicated attraction for holes around the grain boundary region. read less X. W. Zhou et al., “A prediction of dislocation‐free CdTe/CdS photovoltaic multilayers via nano‐patterning and composition grading,” Progress in Photovoltaics: Research and Applications. 2015. link Times cited: 12 Abstract: Defects in multilayered films have long been a performance‐l… read more Abstract: Defects in multilayered films have long been a performance‐limiting problem for the semiconductor industry. For instance, CdTe/CdS solar cell efficiencies have had significant improvement in the past 15years or more without addressing the problem of high misfit dislocation densities. Overcoming this stagnation requires a fundamental understanding of interfacial defect formation. Herein, we demonstrate a new first principles‐based CdTe bond‐order approach that enables efficient molecular dynamics to approach the fidelity of density functional theory. Stringent quantum‐mechanical verification and experimental validation tests reveal that our new approach provides an accurate prediction of defects that earlier methods cannot. Using this new capability, we show that misfit dislocations in CdTe/CdS multilayers can be significantly reduced via nano‐patterning and composition grading and more importantly, dislocation‐free multilayers naturally arise when the pattern dimension is reduced below 90nm. Our predictive methods are generally applicable to other materials, highlighting a rational approach towards low‐defect semiconductor films. Copyright © 2015 John Wiley & Sons, Ltd. read less Y. Mulugeta and H. Woldeghebriel, “Size effect on the structural and electronic properties of lead telluride clusters,” International Journal of Quantum Chemistry. 2015. link Times cited: 3 Abstract: Theoretical computations of (PbTe)n (n = 21–45) clusters bas… read more Abstract: Theoretical computations of (PbTe)n (n = 21–45) clusters based on density functional theory have demonstrated that at cluster size of (PbTe)22 there is a transition from the strong preference of fivefold coordination to sixfold coordination of lead and tellurium atoms. (PbTe)24 cluster is the smallest tetragonal structure in which its central atoms have bulk-like coordination. This quantum dot (QD) contains a single-unit cell of lead telluride crystal, thus can be considered as an “infant crystal.” (PbTe)32 cluster is a perfectly cubic cluster for which its inner (PbTe)4 core enjoys bulk-like coordination. This (PbTe)4 core unit of (PbTe)32 cubic cluster has exactly the same environment as a primitive cell of lead telluride crystal. The (PbTe)8n, (n ≥ 3) clusters are the magic number species with bulk-like structure such that (n = 3–5) the nanoblocks considered here (PbTe)24, (PbTe)32, and (PbTe)40 clusters exhibiting bulk-like structure that can be replicated to obtain the bulk crystal. The calculated dimensions of this special clusters provided a rubric for understanding the pattern of aggregation, that is, the creation of defined nanoblocks [(PbTe)8n, (n ≥ 6)], when they were accumulated on an appropriate surface. It is evident that the QDs (PbTe)8n, (n = 3–5) clusters show high stability compared to their neighboring clusters. This can also be seen from the second-order energy difference, binding, and fragmentation energy graphs. © 2014 Wiley Periodicals, Inc. read less X. W. Zhou, D. Ward, M. Foster, and J. Zimmerman, “An analytical bond-order potential for the copper–hydrogen binary system,” Journal of Materials Science. 2015. link Times cited: 18 D. Kwon, Y. Shim, J. Amar, and A. Compaan, “Grain growth, anomalous scaling, and grain boundary grooving in polycrystalline CdTe thin films,” Journal of Applied Physics. 2014. link Times cited: 11 Abstract: We examine the evolution of the surface morphology as well a… read more Abstract: We examine the evolution of the surface morphology as well as the dynamics of grain growth and grain boundary (GB) grooving in polycrystalline CdTe films sputter deposited on CdS/glass substrates. Anomalous scaling behavior is found with local roughness exponent αloc = 1 and global (local) growth exponent β = 0.36 (βloc = 0.14). In good agreement with the scaling relation, βloc = β − nαloc, we obtain the correlation length exponent n=1/z≃0.23. We also find that the grain size coarsening exponent p and GB groove growth exponent βg are both equal to β, while the grain size distribution is well described by a log-normal distribution. These results suggest that GB grooving is responsible for the enhanced anomalous scaling and a deviation from the theoretical prediction of p = 1/2, along with the observed log-normal grain size distribution. read less X. Zhou, M. E. Foster, F. Swol, J. E. Martin, and B. M. Wong, “Analytical Bond-Order Potential for the Cd–Te–Se Ternary System,” Journal of Physical Chemistry C. 2014. link Times cited: 13 X. W. Zhou, J. J. Chavez, J. Cruz-Campa, and D. Zubia, “Towards model-guided defect reduction in Cd1−xZnxTe/CdS solar cells: Development of molecular dynamics models,” 2014 IEEE 40th Photovoltaic Specialist Conference (PVSC). 2014. link Times cited: 0 Abstract: Cd1-xZnxTe/CdS solar cells are currently limited by material… read more Abstract: Cd1-xZnxTe/CdS solar cells are currently limited by material defects. While nano-structuring promises further defect reductions, the materials synthesis and characterization become more challenging. Molecular dynamics models capable of growth simulations enable defects to be explored without assumptions, and can therefore guide nanoscale experiments. Such models are difficult to develop, and are not routinely available in literature for semiconductor compounds. To fill this gap, we have developed growth simulation enabling Stillinger-Weber and bond-order potentials. These new models begin to enable molecular dynamics to be used to explore nano-structured Cd1-xZnxTe/CdS solar cells with reduced defects. read less J. J. Chavez, X. W. Zhou, D. Ward, J. Cruz-Campa, and D. Zubia, “A molecular dynamics study on defect reduction in thin film Cd1−xZnxTe/CdS solar cells,” 2014 IEEE 40th Photovoltaic Specialist Conference (PVSC). 2014. link Times cited: 1 Abstract: Recently developed molecular dynamics models have been appli… read more Abstract: Recently developed molecular dynamics models have been applied to study the formation of defects during growth of ZnTe-on-CdS multilayers. Our studies indicated that misfit dislocations are formed during growth, and the dislocation density can be reduced if the ZnTe layer is grown in a nano island configuration as opposed to a continuous film. These results highlight the use of molecular dynamics methods in providing valuable defect formation mechanism insight and guiding experimental efforts to produce high efficiency Cd1-xZnxTe solar cells. read less X. Hu, R. Ciaglia, F. Pietrucci, G. A. Gallet, and W. Andreoni, “DFT-derived reactive potentials for the simulation of activated processes: the case of CdTe and CdTe:S.,” The journal of physical chemistry. B. 2014. link Times cited: 2 Abstract: We introduce a new ab initio derived reactive potential for … read more Abstract: We introduce a new ab initio derived reactive potential for the simulation of CdTe within density functional theory (DFT) and apply it to calculate both static and dynamical properties of a number of systems (bulk solid, defective structures, liquid, surfaces) at finite temperature. In particular, we also consider cases with low sulfur concentration (CdTe:S). The analysis of DFT and classical molecular dynamics (MD) simulations performed with the same protocol leads to stringent performance tests and to a detailed comparison of the two schemes. Metadynamics techniques are used to empower both Car-Parrinello and classical molecular dynamics for the simulation of activated processes. For the latter, we consider surface reconstruction and sulfur diffusion in the bulk. The same procedures are applied using previously proposed force fields for CdTe and CdTeS materials, thus allowing for a detailed comparison of the various schemes. read less D. Ward, X. W. Zhou, B. M. Wong, and F. Doty, “A refined parameterization of the analytical Cd–Zn–Te bond-order potential,” Journal of Molecular Modeling. 2013. link Times cited: 13 P. Mukherjee, B. C. Gupta, and P. Jena, “Electronic and magnetic properties of pristine and transition metal doped ZnTe nanowires,” Journal of Physics: Condensed Matter. 2013. link Times cited: 6 Abstract: We have carried out density functional theory based calculat… read more Abstract: We have carried out density functional theory based calculations for understanding the structural, electronic and magnetic properties of pristine and transition metal (TM) doped ZnTe nanowires. Pristine ZnTe nanowires (NWs) turn out to be semiconducting in nature, with the band gap varying with the diameter of the NWs. In Mn-doped ZnTe NWs, the Mn atoms retain a magnetic moment of 5 μB each and couple anti-ferromagnetically. A half metallic ferromagnetic state, although energetically not favorable, is observed arising from a strong hybridization between the d-states of Mn atoms and p-states of Te atoms. Further studies of V- and Sc-doped ZnTe NWs reveal the systems to be anti-ferromagnetic. read less M. Brik, “First-principles calculations of the structural, electronic, optical and elastic properties of the CuYS2 semiconductor,” Journal of Physics: Condensed Matter. 2013. link Times cited: 23 Abstract: The ternary semiconductor CuYS2 is studied by using the firs… read more Abstract: The ternary semiconductor CuYS2 is studied by using the first-principles methods in the density functional theory (DFT) framework. The structural, electronic, optical and elastic properties were calculated at the ambient and elevated hydrostatic pressures. The compound was shown to have an indirect band gap of about 1.342/1.389 eV (in the generalized gradient and local density approximations, respectively). The anisotropy of the optical properties was studied by calculating the absorption spectra, dielectric function and index of refraction for different polarizations. The anisotropy of the elastic properties was visualized by plotting the three-dimensional dependence of the Young’s moduli on the direction in the crystal lattice. The obtained results, which are reported for the first time to the best of the author’s knowledge, can facilitate assessment of possible applications of the title material. read less D. Ward, X. W. Zhou, B. M. Wong, F. Doty, and J. Zimmerman, “Analytical bond-order potential for the Cd-Zn-Te ternary system,” Physical Review B. 2012. link Times cited: 32 Abstract: CdTe/CdSe core/shell structured quantum dots do not suffer f… read more Abstract: CdTe/CdSe core/shell structured quantum dots do not suffer from the defects typically seen in lattice-mismatched films and can therefore lead to improved solid-state lighting devices as compared to the multilayered structures (e.g., InxGa1–xN/GaN). To achieve these devices, however, the quantum dots must be optimized with respect to the structural details at an atomistic level. Molecular dynamics simulations are effective for exploring nano structures at a resolution unattainable by experimental techniques. To enable accurate molecular dynamics simulations of CdTe/CdSe core/shell structures, we have developed a full Cd–Te–Se ternary bond-order potential based on the analytical formalisms derived from quantum mechanical theories by Pettifor et al. A variety of elemental and compound configurations (with coordination varying from 1 to 12) including small clusters, bulk lattices, defects, and surfaces are explicitly considered during potential parametrization. More importantly, enormous iterations are perfor... read less C. Henager, F. Gao, S. Hu, G. Lin, E. Bylaska, and N. Zabaras, “Simulating Interface Growth and Defect Generation in CZT – Simulation State of the Art and Known Gaps.” 2012. link Times cited: 1 Abstract: This one-year, study topic project will survey and investiga… read more Abstract: This one-year, study topic project will survey and investigate the known state-of-the-art of modeling and simulation methods suitable for performing fine-scale, fully 3-D modeling, of the growth of CZT crystals at the melt-solid interface, and correlating physical growth and post-growth conditions with generation and incorporation of defects into the solid CZT crystal. In the course of this study, this project will also identify the critical gaps in our knowledge of modeling and simulation techniques in terms of what would be needed to be developed in order to perform accurate physical simulations of defect generation in melt-grown CZT. The transformational nature of this study will be, for the first time, an investigation of modeling and simulation methods for describing microstructural evolution during crystal growth and the identification of the critical gaps in our knowledge of such methods, which is recognized as having tremendous scientific impacts for future model developments in a wide variety of materials science areas. read less I. Camps, J. Coutinho, M. Mir, A. D. Cunha, M. Rayson, and P. Briddon, “Elastic and optical properties of Cu2ZnSn(SexS1 − x)4 alloys: density functional calculations,” Semiconductor Science and Technology. 2012. link Times cited: 22 Abstract: Cu2ZnSn(S1 − xSex)4 (CZT(S, Se)) is emerging as a very credi… read more Abstract: Cu2ZnSn(S1 − xSex)4 (CZT(S, Se)) is emerging as a very credible alternative to CuIn1 − xGaxSe2 (CIGS) as the absorber layer for thin film solar cells. The former compound has the important advantage of using abundant Zn and Sn instead of the expensive In and Ga. A better understanding of the properties of CZT(S, Se) is being sought through experimental and theoretical means. Thus far, however, very little is known about the fundamental properties of the CZT(S, Se) alloys. In this work, theoretical studies on the structural, elastic, electronic and optical properties of CZT(S, Se) alloys through first-principles calculations are reported. We use a density functional code (aimpro), along with the Padé parametrization for the local density approximation to the exchange correlation potential. For the alloying calculations we employed 64 atom supercells (approximately cubic) with a 2 × 2 × 2 k-point sampling set. These supercells possess a total of 32 chalcogen species and the CZTSexS1 − x alloys are described by using the ordered alloy approximation. Accordingly, to create a perfectly diluted alloying host, the species type of the 32 chalcogen sites is selected randomly with uniform probability x and 1 − x for Se and S, respectively. Properties of alloys (structural, elastic, electronic and optical) are obtained by averaging the results of ten supercell configurations generated for each composition. For each configuration, lattice vectors and atomic positions were allowed to relax (although enforcing the tetragonal lattice type) and the Murnaghan equation of state was fitted to the total energy data. The results presented here permit a better understanding of the properties of the CZT(S, Se) alloys which in turn result in the design of more efficient solar cells. read less J. Cruz-Campa et al., “Nanopatterning and bandgap grading to reduce defects in CdTe solar cells,” 2012 38th IEEE Photovoltaic Specialists Conference. 2012. link Times cited: 5 Abstract: We present simulation and experimental results proving the f… read more Abstract: We present simulation and experimental results proving the feasibility of a novel concept to increase efficiency of CdTe based solar cells. In order to achieve $0.50/W price in CdTe based modules, higher efficiencies need to be attained. The high defect density due to lattice-mismatch between CdS and CdTe reduces lifetime, voltage, and efficiency of the cells. We propose the use of a graded composition structure and a patterned substrate to reduce defects, increase lifetime, and efficiency of the cells. Innovative simulations using high-fidelity molecular dynamics predict that defect-free films are possible if the CdTe film is graded with Zn and is constructed as nano-islands with sizes below 90 nm. Both graded structure and nano-islands reduce the lattice-mismatch stresses. Also, the graded composition creates a back surface field and an enhanced ohmic contact. We have attempted to grow ZnTe and CdTe films on CdS substrates using a template of micro and nano-islands. Selective growths on patterned substrates have shown fewer grain boundaries when the island size decreases below 300 nm. Also, larger grain sizes were obtained using a CdTe/ZnTe stack when compared to a single layer CdTe. The simulation and experimental results demonstrate for the first time the ability to use nanopatterned substrates to enhance uniformity in thin film solar cells. read less D. Ward, X. W. Zhou, B. M. Wong, F. Doty, and J. Zimmerman, “Accuracy of existing atomic potentials for the CdTe semiconductor compound.,” The Journal of chemical physics. 2011. link Times cited: 35 Abstract: CdTe and CdTe-based Cd(1-x)Zn(x)Te (CZT) alloys are importan… read more Abstract: CdTe and CdTe-based Cd(1-x)Zn(x)Te (CZT) alloys are important semiconductor compounds that are used in a variety of technologies including solar cells, radiation detectors, and medical imaging devices. Performance of such systems, however, is limited due to the propensity of nano- and micro-scale defects that form during crystal growth and manufacturing processes. Molecular dynamics simulations offer an effective approach to study the formation and interaction of atomic scale defects in these crystals, and provide insight on how to minimize their concentrations. The success of such a modeling effort relies on the accuracy and transferability of the underlying interatomic potential used in simulations. Such a potential must not only predict a correct trend of structures and energies of a variety of elemental and compound lattices, defects, and surfaces but also capture correct melting behavior and should be capable of simulating crystalline growth during vapor deposition as these processes sample a variety of local configurations. In this paper, we perform a detailed evaluation of the performance of two literature potentials for CdTe, one having the Stillinger-Weber form and the other possessing the Tersoff form. We examine simulations of structures and the corresponding energies of a variety of elemental and compound lattices, defects, and surfaces compared to those obtained from ab initio calculations and experiments. We also perform melting temperature calculations and vapor deposition simulations. Our calculations show that the Stillinger-Weber parameterization produces the correct lowest energy structure. This potential, however, is not sufficiently transferrable for defect studies. Origins of the problems of these potentials are discussed and insights leading to the development of a more transferrable potential suitable for molecular dynamics simulations of defects in CdTe crystals are provided. read less M. Kurban, “MOLECULAR DYNAMICS STUDY ON THE STRUCTURAL, THERMAL AND ENERGETIC PROPERTIES OF GaAs NANOPARTICLES,” Anadolu University Journal of Science and Technology-A Applied Sciences and Engineering. 2018. link Times cited: 1 Abstract: In this work, the structural and energetic properties of GaA… read more Abstract: In this work, the structural and energetic properties of GaAs nanoparticles (NPs) are investigated using the bond order potential (BOP) based on modern classical molecular dynamics (MD) method. All MD simulations are performed by means of LAMMPS. Some physical properties such as variation of potential energy depending on temperature, order parameter, coordination number in terms of probability distribution and radial distribution function (RDF) are searched. The heat capacity calculation is also performed as depending on temperature using a non-equilibrated molecular dynamics simulation strategy. Temperature dependence of these physical properties was obtained. The calculated physical properties are found to be sensitive to temperature. read less X. W. Zhou and R. Jones, “A Stillinger-Weber Potential for InGaN,” Journal of Materials Science Research. 2017. link Times cited: 9 Abstract: Reducing defects in InGaN films deposited on GaN substrates … read more Abstract: Reducing defects in InGaN films deposited on GaN substrates has been critical to fill the “green” gap for solid-state lighting applications. To enable researchers to use molecular dynamics vapor deposition simulations to explores ways to reduce defects in InGaN films, we have developed and characterized a Stillinger-Weber potential for InGaN. We show that this potential reproduces the experimental atomic volume, cohesive energy, and bulk modulus of the equilibrium wurtzite / zinc-blende phases of both InN and GaN. Most importantly, the potential captures the stability of the correct phase of InGaN compounds against a variety of other elemental, alloy, and compound configurations. This is validated by the potential’s ability to predict crystalline growth of stoichiometric wurtzite and zinc-blende InxGa1-xN compounds during vapor deposition simulations where adatoms are randomly injected to the growth surface. read less S. Winczewski, J. Dziedzic, and J. Rybicki, “Central-force decomposition of spline-based modified embedded atom method potential,” Modelling and Simulation in Materials Science and Engineering. 2016. link Times cited: 0 Abstract: Central-force decompositions are fundamental to the calculat… read more Abstract: Central-force decompositions are fundamental to the calculation of stress fields in atomic systems by means of Hardy stress. We derive expressions for a central-force decomposition of the spline-based modified embedded atom method (s-MEAM) potential. The expressions are subsequently simplified to a form that can be readily used in molecular-dynamics simulations, enabling the calculation of the spatial distribution of stress in systems treated with this novel class of empirical potentials. We briefly discuss the properties of the obtained decomposition and highlight further computational techniques that can be expected to benefit from the results of this work. To demonstrate the practicability of the derived expressions, we apply them to calculate stress fields due to an edge dislocation in bcc Mo, comparing their predictions to those of linear elasticity theory. read less
Funding	Not available

Short KIM ID The unique KIM identifier code.	SM_509819366101_001
Extended KIM ID The long form of the KIM ID including a human readable prefix (100 characters max), two underscores, and the Short KIM ID. Extended KIM IDs can only contain alpha-numeric characters (letters and digits) and underscores and must begin with a letter.	Sim_LAMMPS_BOP_WardZhouWong_2012_CdTe__SM_509819366101_001
DOI	10.25950/5c67ce36 https://doi.org/10.25950/5c67ce36 https://commons.datacite.org/doi.org/10.25950/5c67ce36
KIM Item Type	Simulator Model
KIM API Version	2.2
Simulator Name The name of the simulator as defined in kimspec.edn.	LAMMPS
Potential Type	bop
Simulator Potential	bop
Run Compatibility	portable-models

Previous Version	Sim_LAMMPS_BOP_WardZhouWong_2012_CdTe__SM_509819366101_000

Verification Check Dashboard

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Grade	Name	Category	Brief Description	Full Results	Aux File(s)
N/A Unable to perform verification check due to an error.	vc-species-supported-as-stated	mandatory	The model supports all species it claims to support; see full description.	Results	Files
N/A Unable to perform verification check due to an error.	vc-periodicity-support	mandatory	Periodic boundary conditions are handled correctly; see full description.	Results	Files
N/A Unable to perform verification check due to an error.	vc-permutation-symmetry	mandatory	Total energy and forces are unchanged when swapping atoms of the same species; see full description.	Results	Files
N/A Unable to perform verification check due to an error.	vc-forces-numerical-derivative	consistency	Forces computed by the model agree with numerical derivatives of the energy; see full description.	Results	Files
F The model is C^0 continuous. This means that the model has continuous energy, but a discontinuous first derivative.	vc-dimer-continuity-c1	informational	The energy versus separation relation of a pair of atoms is C1 continuous (i.e. the function and its first derivative are continuous); see full description.	Results	Files
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This bar chart plot shows the mono-atomic body-centered cubic (bcc) lattice constant predicted by the current model (shown in the unique color) compared with the predictions for all other models in the OpenKIM Repository that support the species. The vertical bars show the average and standard deviation (one sigma) bounds for all model predictions. Graphs are generated for each species supported by the model.

(No matching species)

Cohesive Energy Graph

This graph shows the cohesive energy versus volume-per-atom for the current mode for four mono-atomic cubic phases (body-centered cubic (bcc), face-centered cubic (fcc), simple cubic (sc), and diamond). The curve with the lowest minimum is the ground state of the crystal if stable. (The crystal structure is enforced in these calculations, so the phase may not be stable.) Graphs are generated for each species supported by the model.

(No matching species)

Diamond Lattice Constant

This bar chart plot shows the mono-atomic face-centered diamond lattice constant predicted by the current model (shown in the unique color) compared with the predictions for all other models in the OpenKIM Repository that support the species. The vertical bars show the average and standard deviation (one sigma) bounds for all model predictions. Graphs are generated for each species supported by the model.

(No matching species)

Dislocation Core Energies

This graph shows the dislocation core energy of a cubic crystal at zero temperature and pressure for a specific set of dislocation core cutoff radii. After obtaining the total energy of the system from conjugate gradient minimizations, non-singular, isotropic and anisotropic elasticity are applied to obtain the dislocation core energy for each of these supercells with different dipole distances. Graphs are generated for each species supported by the model.

(No matching species)

FCC Elastic Constants

This bar chart plot shows the mono-atomic face-centered cubic (fcc) elastic constants predicted by the current model (shown in blue) compared with the predictions for all other models in the OpenKIM Repository that support the species. The vertical bars show the average and standard deviation (one sigma) bounds for all model predictions. Graphs are generated for each species supported by the model.

(No matching species)

FCC Lattice Constant

This bar chart plot shows the mono-atomic face-centered cubic (fcc) lattice constant predicted by the current model (shown in red) compared with the predictions for all other models in the OpenKIM Repository that support the species. The vertical bars show the average and standard deviation (one sigma) bounds for all model predictions. Graphs are generated for each species supported by the model.

(No matching species)

FCC Stacking Fault Energies

This bar chart plot shows the intrinsic and extrinsic stacking fault energies as well as the unstable stacking and unstable twinning energies for face-centered cubic (fcc) predicted by the current model (shown in blue) compared with the predictions for all other models in the OpenKIM Repository that support the species. The vertical bars show the average and standard deviation (one sigma) bounds for all model predictions. Graphs are generated for each species supported by the model.

(No matching species)

FCC Surface Energies

This bar chart plot shows the mono-atomic face-centered cubic (fcc) relaxed surface energies predicted by the current model (shown in blue) compared with the predictions for all other models in the OpenKIM Repository that support the species. The vertical bars show the average and standard deviation (one sigma) bounds for all model predictions. Graphs are generated for each species supported by the model.

(No matching species)

SC Lattice Constant

This bar chart plot shows the mono-atomic simple cubic (sc) lattice constant predicted by the current model (shown in the unique color) compared with the predictions for all other models in the OpenKIM Repository that support the species. The vertical bars show the average and standard deviation (one sigma) bounds for all model predictions. Graphs are generated for each species supported by the model.

(No matching species)

Cubic Crystal Basic Properties Table

Species: Cd

Species: Te

Tests

EquilibriumCrystalStructure__TD_457028483760_002

Equilibrium structure and energy for a crystal structure at zero temperature and pressure v002

Creators:
Contributor: ilia
Publication Year: 2024
DOI: https://doi.org/10.25950/2f2c4ad3

Computes the equilibrium crystal structure and energy for an arbitrary crystal at zero temperature and applied stress by performing symmetry-constrained relaxation. The crystal structure is specified using the AFLOW prototype designation. Multiple sets of free parameters corresponding to the crystal prototype may be specified as initial guesses for structure optimization. No guarantee is made regarding the stability of computed equilibria, nor that any are the ground state.

Test	Link to Test Results page	Benchmark time Usertime multiplied by the Whetstone Benchmark. This number can be used (approximately) to compare the performance of different models independently of the architecture on which the test was run. Measured in Millions of Whetstone Instructions (MWI)
Equilibrium crystal structure and energy for Te in AFLOW crystal prototype A_cP1_221_a v002	view	55170
Equilibrium crystal structure and energy for CdTe in AFLOW crystal prototype AB_cF8_216_a_c v002	view	136566
Equilibrium crystal structure and energy for CdTe in AFLOW crystal prototype AB_cF8_225_a_b v002	view	72122
Equilibrium crystal structure and energy for CdTe in AFLOW crystal prototype AB_hP4_186_b_b v002	view	55656

EquilibriumCrystalStructure__TD_457028483760_003

Equilibrium structure and energy for a crystal structure at zero temperature and pressure v003

Creators:
Contributor: ilia
Publication Year: 2025
DOI: https://doi.org/10.25950/866c7cfa

Computes the equilibrium crystal structure and energy for an arbitrary crystal at zero temperature and applied stress by performing symmetry-constrained relaxation. The crystal structure is specified using the AFLOW prototype designation. Multiple sets of free parameters corresponding to the crystal prototype may be specified as initial guesses for structure optimization. No guarantee is made regarding the stability of computed equilibria, nor that any are the ground state.

Test	Test Results	Link to Test Results page	Benchmark time Usertime multiplied by the Whetstone Benchmark. This number can be used (approximately) to compare the performance of different models independently of the architecture on which the test was run. Measured in Millions of Whetstone Instructions (MWI)
Equilibrium crystal structure and energy for Cd in AFLOW crystal prototype A_hP2_194_c v003		view	155606

Errors

EquilibriumCrystalStructure__TD_457028483760_002

Test	Error Categories	Link to Error page
Equilibrium crystal structure and energy for Te in AFLOW crystal prototype A_hP3_152_a v002	other	view
Equilibrium crystal structure and energy for Te in AFLOW crystal prototype A_hR1_166_a v002	other	view
Equilibrium crystal structure and energy for Te in AFLOW crystal prototype A_oC2_65_a v002	other	view
Equilibrium crystal structure and energy for Te in AFLOW crystal prototype A_oP4_26_2a v002	other	view
Equilibrium crystal structure and energy for Te in AFLOW crystal prototype A_oP4_55_g v002	other	view
Equilibrium crystal structure and energy for CdTe in AFLOW crystal prototype AB_hP6_152_a_b v002	other	view
Equilibrium crystal structure and energy for CdTe in AFLOW crystal prototype AB_oC8_63_c_c v002	other	view
Equilibrium crystal structure and energy for CdTe in AFLOW crystal prototype AB_oP2_25_a_b v002	other	view

LatticeConstantCubicEnergy__TD_475411767977_007

Test	Error Categories	Link to Error page
Equilibrium zero-temperature lattice constant for bcc Cd v007	other	view
Equilibrium zero-temperature lattice constant for bcc Te v007	other	view
Equilibrium zero-temperature lattice constant for diamond Cd v007	other	view
Equilibrium zero-temperature lattice constant for diamond Te v007	other	view
Equilibrium zero-temperature lattice constant for fcc Cd v007	other	view
Equilibrium zero-temperature lattice constant for fcc Te v007	other	view
Equilibrium zero-temperature lattice constant for sc Cd v007	other	view
Equilibrium zero-temperature lattice constant for sc Te v007	other	view

LatticeConstantHexagonalEnergy__TD_942334626465_005

Test	Error Categories	Link to Error page
Equilibrium lattice constants for hcp Cd v005	other	view
Equilibrium lattice constants for hcp Te v005	other	view

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Verification Check	Error Categories	Link to Error page
PeriodicitySupport__VC_895061507745_004	other	view

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CMakeLists.txt
CdTe.bop.table
LICENSE
kimprovenance.edn
kimspec.edn
smspec.edn

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Sim_LAMMPS_BOP_WardZhouWong_2012_CdTe__SM_509819366101_001

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BCC Lattice Constant

Cohesive Energy Graph

Diamond Lattice Constant

Dislocation Core Energies

FCC Elastic Constants

FCC Lattice Constant

FCC Stacking Fault Energies

FCC Surface Energies

SC Lattice Constant

Cubic Crystal Basic Properties Table

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