This is an analytical NN EAM model for Cu by Johnson.

Jump to: Tests | Visualizers | Files | Wiki

EAM_Johnson_NearestNeighbor_Cu__MO_887933271505_000

There is a newer version of this item. See EAM_NN_Johnson_1988_Cu__MO_887933271505_003

Interatomic potential for Copper (Cu).
Use this Potential

Title A single sentence description.	This is an analytical NN EAM model for Cu by Johnson.
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.	This is an analytical NN EAM model for Cu by Johnson.
Species The supported atomic species.	Cu
Disclaimer A statement of applicability provided by the contributor, informing users of the intended use of this KIM Item.	None

Contributor	Ryan S. Elliott
Maintainer	Ryan S. Elliott
Published on KIM	2014
How to Cite	Click here to download this citation in BibTeX format.
Funding	Not available

Short KIM ID The unique KIM identifier code.	MO_887933271505_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_Johnson_NearestNeighbor_Cu__MO_887933271505_000
Citable Link	https://openkim.org/cite/MO_887933271505_000
KIM Item Type Specifies whether this is a Portable Model (software implementation of an interatomic model); Portable Model with parameter file (parameter file to be read in by a Model Driver); Model Driver (software implementation of an interatomic model that reads in parameters).	Portable Model
KIM API Version	1.5
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.	100.00% C

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: Cu

Tests

Disclaimer From Model Developer

None

No Tests associated with this Model
Tests are paired to Models through Test Results

Errors

No Errors associated with this Model

Files

EAM_Johnson_NearestNeighbor_Cu__MO_887933271505_000.c
EAM_Johnson_NearestNeighbor_Cu__MO_887933271505_000.kim
LICENSE.CDDL
Makefile
README
kimprovenance.edn
kimspec.edn

Download

EAM_Johnson_NearestNeighbor_Cu__MO_887933271505_000.txz	Tar+XZ	Linux and OS X archive
EAM_Johnson_NearestNeighbor_Cu__MO_887933271505_000.zip	Zip	Windows archive

Wiki

Wiki is ready to accept new content.

Parameter Choices in the SW Potential

In the original Stillinger-Weber paper (SW85: PRB 31:5262, 1985) it is stated that in order to obtain the correct “atomization energy” (cohesive energy) the following choice for epsilon must be made (see Eqn. (2.9) in [SW85]):

epsilon = 50 kcal/mol = 3.4723E-12 erg/atom

Unfortunately, there appears to be an error in the unit conversion here. (There is also an indeterminacy associated with the “kcal” unit which can mean different things.) The kcal and erg values have led to two different values for epsilon being used in articles that cite [SW85].

(a) If the kcal number is selected (assuming that S&W meant the thermochemical kcal unit), then epsilon = 2.1682 eV. This can be seen from the following conversion (which uses NIST conversion factors):

(50 kcal_th/mol)/(6.02214129 mol^-1) = 8.30269461E-23 kcal_th

8.30269461E-23 kcal_th x 4.184E+03 (J/kcal_th) = 3.47384742E-19 J

3.47384742E-19 J x 6.24150934E+18 (eV/J) = 2.168205112 eV

(b) If the erg number is selected, then epsilon = 2.1672 eV, which follows from:

3.4723E-12 erg x 6.24150934E+11 (eV/erg) = 2.16723929 eV

As noted above, both values have been used in simulations that cite the original [SW85] paper. However, it appears that S&W intended to use the 50 kcal_th/mol value since they refer to this number more than once in the paper. (See for example discussion after Eqn. (8.1) in [SW85].) Therefore we argue that the appropriate choice is

epsilon = 8.30269461E-23 kcal_th

or in eV units (reduced to 5-digit significant digits):

epsilon = 2.1682 eV

Note that in the Si.sw parameterization for this potential distributed with LAMMPS, a value of epsilon=2.1683 is used, which appears to be due to slightly different unit conversion.

Another source of confusion is that in [SW85] the potential is fitted to an incorrect value for the cohesive energy of silicon. This is corrected by Balamane in a 1992 paper. See https://openkim.org/cite/MO_113686039439_004 for more details.

SW Functions

See the Stillinger-Weber Model driver page (linked above) for the definition of the model and its functions. The graphs below are for the Stillinger-Weber parametrization for silicon.

The graph of function $f_{2}$ with the parameter values suggested by Stillinger and Weber ( $A = 7.049556277$ , $B = 0.6022245584$ , $p = 4$ , $q = 0$ , $a = 1.80$ ) is given in the following Figure:

The contour plot of the function $h$ in $f_{3}$ for $θ = \cos^{- 1} (- 0.25) = {104.48}^{\circ}$ , as a function of $r_{i j}$ and $r_{i k}$ is given below:

EAM_Johnson_NearestNeighbor_Cu__MO_887933271505_000

Visualizers (in-page)

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

Tests

Disclaimer From Model Developer

Errors

Files

Download

Wiki

Parameter Choices in the SW Potential

SW Functions