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Implement born_matrix in pair_buck_coul_cut.cpp

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This commit is contained in:
Evangelos Voyiatzis
2023-03-01 12:38:23 +02:00
committed by GitHub
parent e0cc7aad97
commit 45009c8c66
1 changed files with 38 additions and 0 deletions
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38
src/pair_buck_coul_cut.cpp
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@ -36,6 +36,7 @@ using namespace MathConst;
PairBuckCoulCut::PairBuckCoulCut(LAMMPS *lmp) : Pair(lmp)
{
born_matrix_enable = 1;
writedata = 1;
}
@ -475,6 +476,43 @@ double PairBuckCoulCut::single(int i, int j, int itype, int jtype, double rsq, d
/* ---------------------------------------------------------------------- */
void PairBuckCoulCut::born_matrix(int i, int j, int itype, int jtype, double rsq,
double factor_coul, double factor_lj, double &dupair,
double &du2pair)
{
double rinv, r2inv, r3inv, r6inv, r7inv, r8inv, r, rexp;
double du_lj, du2_lj, du_coul, du2_coul;
double *q = atom->q;
double qqrd2e = force->qqrd2e;
r = sqrt(rsq);
rexp = exp(-r*rhoinv[itype][jtype]);
r2inv = 1.0 / rsq;
rinv = sqrt(r2inv);
r3inv = r2inv * rinv;
r6inv = r2inv * r2inv * r2inv;
r7inv = r6inv * rinv;
r8inv = r6inv * r2inv;
// Reminder: buck1[itype][jtype] = a[itype][jtype]/rho[itype][jtype];
// Reminder: buck2[itype][jtype] = 6.0*c[itype][jtype];
du_lj = buck2[itype][jtype] * r7inv - buck1[itype][jtype] * rexp;
du2_lj = (buck1[itype][jtype] / rho[itype][jtype]) * rexp - 7 * buck2[itype][jtype] * r8inv;
// Reminder: qqrd2e converts q^2/r to energy w/ dielectric constant
du_coul = -qqrd2e * q[i] * q[j] * r2inv;
du2_coul = 2.0 * qqrd2e * q[i] * q[j] * r3inv;
dupair = factor_lj * du_lj + factor_coul * du_coul;
du2pair = factor_lj * du2_lj + factor_coul * du2_coul;
}
/* ---------------------------------------------------------------------- */
void *PairBuckCoulCut::extract(const char *str, int &dim)
{
dim = 2;