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EAM_Dynamo_NicholAckland_2016v2_Cs__MO_144828415103_000

Title
A single sentence description.
Finnis-Sinclair potential (LAMMPS cubic hermite tabulation) for Cs developed by Nichol and Ackland (2016), version 2 refitted for better elastic constants v000
Description
A short description of the Model describing its key features including for example: type of model (pair potential, 3-body potential, EAM, etc.), modeled species (Ac, Ag, ..., Zr), intended purpose, origin, and so on.
Finnis-Sinclair potential for Cs developed by Nichol and Ackland (2016) fitted precisely to cohesive and vacancy energies, elastic moduli, the lattice parameter, and crystal stability. Remarkably good agreement with the experimental melting temperature is obtained by simulating the equilibration of solid and liquid samples in thermal contact at ambient pressure. No forces or finite-temperature properties are included in the fit, so this demonstrates a surprisingly high level of intrinsic transferability in this simple potential. Currently, there are few potentials available for the alkali metals, so in addition to demonstrating trends in behavior, we expect that the potential will be of broad general use.

According to the developer Graeme Ackland (as reported by the NIST IPRP) version 2 addresses a spurious oscillation period in the tabulated r*phi function that influenced measurements, most notably static elastic constant evaluations.
Species
The supported atomic species.
Cs
Content Origin NIST IPRP (https://www.ctcms.nist.gov/potentials/Cs.html)
Content Other Locations http://homepages.ed.ac.uk/graeme/moldy/moldy.html
Contributor tadmor
Maintainer tadmor
Author Ellad Tadmor
Publication Year 2018
Source Citations
A citation to primary published work(s) that describe this KIM Item.

Nichol A, Ackland GJ (2016) Property trends in simple metals: An empirical potential approach. Phys Rev B 93(18):184101. doi:10.1103/PhysRevB.93.184101

Item Citation Click here to download a citation in BibTeX format.
Short KIM ID
The unique KIM identifier code.
MO_144828415103_000
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.
EAM_Dynamo_NicholAckland_2016v2_Cs__MO_144828415103_000
DOI 10.25950/22f9dbd5
https://doi.org/10.25950/22f9dbd5
https://search.datacite.org/works/10.25950/22f9dbd5
KIM Item Type
Specifies whether this is a Stand-alone Model (software implementation of an interatomic model); Parameterized Model (parameter file to be read in by a Model Driver); Model Driver (software implementation of an interatomic model that reads in parameters).
Parameterized Model using Model Driver EAM_Dynamo__MD_120291908751_005
DriverEAM_Dynamo__MD_120291908751_005
KIM API Version2.0
Programming Language(s)
The programming languages used in the code and the percentage of the code written in each one. "N/A" means "not applicable" and refers to model parameterizations which only include parameter tables and have no programming language.
N/A

Verification Check Dashboard

(Click here to learn more about Verification Checks)

Grade Name Category Brief Description Full Results Aux File(s)
P vc-species-supported-as-stated mandatory
The model supports all species it claims to support; see full description.
Results Files
P vc-periodicity-support mandatory
Periodic boundary conditions are handled correctly; see full description.
Results Files
P vc-permutation-symmetry mandatory
Total energy and forces are unchanged when swapping atoms of the same species; see full description.
Results Files
A vc-forces-numerical-derivative consistency
Forces computed by the model agree with numerical derivatives of the energy; see full description.
Results Files
P 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
P vc-objectivity informational
Total energy is unchanged and forces transform correctly under rigid-body translation and rotation; see full description.
Results Files
P vc-inversion-symmetry informational
Total energy is unchanged and forces change sign when inverting a configuration through the origin; see full description.
Results Files
P vc-memory-leak informational
The model code does not have memory leaks (i.e. it releases all allocated memory at the end); see full description.
Results Files
P vc-thread-safe mandatory
The model returns the same energy and forces when computed in serial and when using parallel threads for a set of configurations. Note that this is not a guarantee of thread safety; see full description.
Results Files

Visualizers (in-page)


BCC Lattice Constant

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.

Species: Cs

Click on any thumbnail to get a full size image.



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.

Species: Cs

Click on any thumbnail to get a full size image.



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.

Species: Cs

Click on any thumbnail to get a full size image.



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.

Species: Cs

Click on any thumbnail to get a full size image.



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.

Species: Cs

Click on any thumbnail to get a full size image.



Cubic Crystal Basic Properties Table

Species: Cs



Tests

CohesiveEnergyVsLatticeConstant__TD_554653289799_002
This Test Driver uses LAMMPS to compute the cohesive energy of a given monoatomic cubic lattice (fcc, bcc, sc, or diamond) at a variety of lattice spacings. The lattice spacings range from a_min (=a_min_frac*a_0) to a_max (=a_max_frac*a_0) where a_0, a_min_frac, and a_max_frac are read from stdin (a_0 is typically approximately equal to the equilibrium lattice constant). The precise scaling and number of lattice spacings sampled between a_min and a_0 (a_0 and a_max) is specified by two additional parameters passed from stdin: N_lower and samplespacing_lower (N_upper and samplespacing_upper). Please see README.txt for further details.
Test Test Results Link to Test Results page Benchmark time
Usertime muliplied 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)
CohesiveEnergyVsLatticeConstant_bcc_Cs__TE_577627611509_002 view 2246
CohesiveEnergyVsLatticeConstant_diamond_Cs__TE_775907885499_002 view 2471
CohesiveEnergyVsLatticeConstant_fcc_Cs__TE_738977471521_002 view 2663
CohesiveEnergyVsLatticeConstant_sc_Cs__TE_291454088501_002 view 2727
ElasticConstantsCubic__TD_011862047401_004
Computes the cubic elastic constants for some common crystal types (fcc, bcc, sc) by calculating the hessian of the energy density with respect to strain. An estimate of the error associated with the numerical differentiation performed is reported.
Test Test Results Link to Test Results page Benchmark time
Usertime muliplied 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)
ElasticConstantsCubic_bcc_Cs__TE_579385355842_004 view 1668
ElasticConstantsCubic_fcc_Cs__TE_285737330496_004 view 1572
ElasticConstantsCubic_sc_Cs__TE_174709371149_004 view 1315
LatticeConstantCubicEnergy__TD_475411767977_006
Equilibrium lattice constant and cohesive energy of a cubic lattice at zero temperature and pressure.
Test Test Results Link to Test Results page Benchmark time
Usertime muliplied 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)
LatticeConstantCubicEnergy_bcc_Cs__TE_629135245492_006 view 963
LatticeConstantCubicEnergy_diamond_Cs__TE_597152627867_006 view 1508
LatticeConstantCubicEnergy_fcc_Cs__TE_463571146589_006 view 963
LatticeConstantCubicEnergy_sc_Cs__TE_880839356614_006 view 1283
SurfaceEnergyCubicCrystalBrokenBondFit__TD_955413365818_003
Calculates the surface energy of several high symmetry surfaces and produces a broken-bond model fit. In latex form, the fit equations are given by:

E_{FCC} (\vec{n}) = p_1 (4 \left( |x+y| + |x-y| + |x+z| + |x-z| + |z+y| +|z-y|\right)) + p_2 (8 \left( |x| + |y| + |z|\right)) + p_3 (2 ( |x+ 2y + z| + |x+2y-z| + |x-2y + z| + |x-2y-z| + |2x+y+z| + |2x+y-z| +|2x-y+z| +|2x-y-z| +|x+y+2z| +|x+y-2z| +|x-y+2z| +|x-y-2z| ) + c

E_{BCC} (\vec{n}) = p_1 (6 \left( | x+y+z| + |x+y-z| + |-x+y-z| + |x-y+z| \right)) + p_2 (8 \left( |x| + |y| + |z|\right)) + p_3 (4 \left( |x+y| + |x-y| + |x+z| + |x-z| + |z+y| +|z-y|\right)) +c.

In Python, these two fits take the following form:

def BrokenBondFCC(params, index):

import numpy
x, y, z = index
x = x / numpy.sqrt(x**2.+y**2.+z**2.)
y = y / numpy.sqrt(x**2.+y**2.+z**2.)
z = z / numpy.sqrt(x**2.+y**2.+z**2.)

return params[0]*4* (abs(x+y) + abs(x-y) + abs(x+z) + abs(x-z) + abs(z+y) + abs(z-y)) + params[1]*8*(abs(x) + abs(y) + abs(z)) + params[2]*(abs(x+2*y+z) + abs(x+2*y-z) +abs(x-2*y+z) +abs(x-2*y-z) + abs(2*x+y+z) +abs(2*x+y-z) +abs(2*x-y+z) +abs(2*x-y-z) + abs(x+y+2*z) +abs(x+y-2*z) +abs(x-y+2*z) +abs(x-y-2*z))+params[3]

def BrokenBondBCC(params, x, y, z):


import numpy
x, y, z = index
x = x / numpy.sqrt(x**2.+y**2.+z**2.)
y = y / numpy.sqrt(x**2.+y**2.+z**2.)
z = z / numpy.sqrt(x**2.+y**2.+z**2.)

return params[0]*6*(abs(x+y+z) + abs(x-y-z) + abs(x-y+z) + abs(x+y-z)) + params[1]*8*(abs(x) + abs(y) + abs(z)) + params[2]*4* (abs(x+y) + abs(x-y) + abs(x+z) + abs(x-z) + abs(z+y) + abs(z-y)) + params[3]
Test Test Results Link to Test Results page Benchmark time
Usertime muliplied 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)
SurfaceEnergyCubicCrystalBrokenBondFit_bcc_Cs__TE_771556685416_003 view 10011





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