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# Copyright (c) 2012, Regents of the University of Minnesota.  All rights reserved.
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# Contributors:
#    Ryan S. Elliott
#    Ellad B. Tadmor
#    Valeriu Smirichinski
#    Amit Singh
#    Mingjian Wen


This directory (Three_Body_Stillinger_Weber_Si__MO_405512056662_004) contains the Stillinger-Weber potential
Model based on the KIM Model Driver Three_Body_Stillinger_Weber.  This Model
implements the Stillinger-Weber potential for Si.

The following files are in this directory:

Three_Body_Stillinger_Weber_Si.params

  first line: 1 (number of species)

  Then the following 9 parameters:
  A(in ev) B p q sigma(in Angstrom) lambda(in eV) gamma(in Angstorm) costheta_0 cutoff

  Any additional lines will be silently ignored.


LICENSE.CDDL
  The Common Development and Distribution License (CDDL) Version 1.0 file

Makefile
  makefile to compile and build the Model based on the specified KIM Model Driver

README
  This file

References:

1. F. H. Stillinger and T. A. Weber, "Computer simulation of local order in condensed phases of silicon", Phys. Rev. B, vol. 31, 5262-5271, 1985

2. Ellad B. Tadmor and Ronald E. Miller, Modeling Materials: Continuum, Atomistic and Multiscale Techniques, Cambridge University Press, 2011



###############################################################################
The functional form of the SW potential is rewritten as:

  E = sum_{i,j>i} phi_2(rij) + sum_{i, j!=i, k>j} phi_3(rij, rik, theta)

  phi_2(rij)           = Aij*(Bij(rij/sigma_ij)^(-p) - (rij/sigma_ij)^(-q))
                         * exp(sigma_ij/(rij - rcutij))

  phi_3(rij,rik,theta) = lambda_ijk(cos[theta] - cos[theta0])^2
                         *  exp(gamma_ij/(rij - rcutij) + gamma_ik/(rik - rcutik))

Compared to the standard SW potential, the following redefinitions have been made:
  A      := A*epsilon
  lambda := lambda*epsilon
  gamma  := gamma*sigma
  rcut   := a*sigma