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pair_tersoff_omp.h
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Sat, Sep 14, 15:25

pair_tersoff_omp.h
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/* -*- c++ -*- ----------------------------------------------------------
LAMMPS - Large-scale Atomic/Molecular Massively Parallel Simulator
http://lammps.sandia.gov, Sandia National Laboratories
Steve Plimpton, sjplimp@sandia.gov
Copyright (2003) Sandia Corporation. Under the terms of Contract
DE-AC04-94AL85000 with Sandia Corporation, the U.S. Government retains
certain rights in this software. This software is distributed under
the GNU General Public License.
See the README file in the top-level LAMMPS directory.
------------------------------------------------------------------------- */
#ifdef PAIR_CLASS
PairStyle(tersoff/omp,PairTersoffOMP)
#else
#ifndef LMP_PAIR_TERSOFF_OMP_H
#define LMP_PAIR_TERSOFF_OMP_H
#include "pair_omp.h"
namespace LAMMPS_NS {
class PairTersoffOMP : public PairOMP {
public:
PairTersoffOMP(class LAMMPS *);
virtual ~PairTersoffOMP();
void compute(int, int);
void settings(int, char **);
void coeff(int, char **);
void init_style();
double init_one(int, int);
protected:
struct Param {
double lam1,lam2,lam3;
double c,d,h;
double gamma,powerm;
double powern,beta;
double biga,bigb,bigd,bigr;
double cut,cutsq;
double c1,c2,c3,c4;
int ielement,jelement,kelement;
int powermint;
double Z_i,Z_j;
double ZBLcut,ZBLexpscale;
};
double PI,PI2,PI4;
double cutmax; // max cutoff for all elements
int nelements; // # of unique elements
char **elements; // names of unique elements
int ***elem2param; // mapping from element triplets to parameters
int *map; // mapping from atom types to elements
int nparams; // # of stored parameter sets
int maxparam; // max # of parameter sets
Param *params; // parameter set for an I-J-K interaction
void allocate();
virtual void read_file(char *);
void setup();
virtual void repulsive(Param *, double, double &, int, double &);
double zeta(Param *, double, double, double *, double *);
void force_zeta(Param *, double, double, double &, double &, int, double &);
void attractive(Param *, double, double, double, double *, double *,
double *, double *, double *);
double ters_fc_d(double, Param *);
virtual double ters_fa(double, Param *);
virtual double ters_fa_d(double, Param *);
double ters_bij(double, Param *);
double ters_bij_d(double, Param *);
void ters_zetaterm_d(double, double *, double, double *, double,
double *, double *, double *, Param *);
void costheta_d(double *, double, double *, double,
double *, double *, double *);
// small methods that are called a *lot* and have no side effects.
inline double ters_fc(const double r, const Param *param) const
{
double ters_R = param->bigr;
double ters_D = param->bigd;
if (r < ters_R-ters_D) return 1.0;
if (r > ters_R+ters_D) return 0.0;
return 0.5*(1.0 - sin(PI2*(r - ters_R)/ters_D));
};
inline double ters_gijk(const double costheta, const Param *param) const {
const double ters_c = param->c;
const double ters_d = param->d;
const double ters_r = ters_c/ters_d;
const double ters_h = param->h - costheta;
return param->gamma*(1.0 + (ters_r*ters_r) - (ters_c*ters_c)
/ ((ters_d*ters_d) + (ters_h*ters_h)));
};
inline double ters_gijk_d(const double costheta, const Param *param) const {
const double ters_c = param->c;
const double ters_d = param->d;
const double ters_h = param->h - costheta;
const double numerator = -2.0 * (ters_c*ters_c) * ters_h;
const double denom = (ters_d*ters_d) + (ters_h*ters_h);
return param->gamma*numerator/(denom*denom);
};
// vector functions, inline for efficiency
inline double vec3_dot(double *x, double *y) const {
return x[0]*y[0] + x[1]*y[1] + x[2]*y[2];
}
inline void vec3_add(double *x, double *y, double *z) const {
z[0] = x[0]+y[0]; z[1] = x[1]+y[1]; z[2] = x[2]+y[2];
}
inline void vec3_scale(double k, double *x, double *y) const {
y[0] = k*x[0]; y[1] = k*x[1]; y[2] = k*x[2];
}
inline void vec3_scaleadd(double k, double *x, double *y, double *z) const {
z[0] = k*x[0]+y[0]; z[1] = k*x[1]+y[1]; z[2] = k*x[2]+y[2];
}
};
}
#endif
#endif

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