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pair_tersoff.h
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Sat, Nov 9, 22:58

pair_tersoff.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,PairTersoff)
#else
#ifndef LMP_PAIR_TERSOFF_H
#define LMP_PAIR_TERSOFF_H
#include "pair.h"
namespace LAMMPS_NS {
class PairTersoff : public Pair {
public:
PairTersoff(class LAMMPS *);
virtual ~PairTersoff();
virtual void compute(int, int);
void settings(int, char **);
void coeff(int, char **);
virtual 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; // added for TersoffZBL
double ZBLcut,ZBLexpscale;
double c5,ca1,ca4; // added for TersoffMOD
double powern_del;
};
Param *params; // parameter set for an I-J-K interaction
char **elements; // names of unique elements
int ***elem2param; // mapping from element triplets to parameters
int *map; // mapping from atom types to elements
double cutmax; // max cutoff for all elements
int nelements; // # of unique elements
int nparams; // # of stored parameter sets
int maxparam; // max # of parameter sets
virtual void allocate();
virtual void read_file(char *);
virtual void setup_params();
virtual void repulsive(Param *, double, double &, int, double &);
virtual double zeta(Param *, double, double, double *, double *);
virtual void force_zeta(Param *, double, double, double &,
double &, int, double &);
void attractive(Param *, double, double, double, double *, double *,
double *, double *, double *);
virtual double ters_fc(double, Param *);
virtual double ters_fc_d(double, Param *);
virtual double ters_fa(double, Param *);
virtual double ters_fa_d(double, Param *);
virtual double ters_bij(double, Param *);
virtual double ters_bij_d(double, Param *);
virtual void ters_zetaterm_d(double, double *, double, double *, double,
double *, double *, double *, Param *);
void costheta_d(double *, double, double *, double,
double *, double *, double *);
// inlined functions for efficiency
inline double ters_gijk(const double costheta,
const Param * const param) const {
const double ters_c = param->c * param->c;
const double ters_d = param->d * param->d;
const double hcth = param->h - costheta;
return param->gamma*(1.0 + ters_c/ters_d - ters_c / (ters_d + hcth*hcth));
}
inline double ters_gijk_d(const double costheta,
const Param * const param) const {
const double ters_c = param->c * param->c;
const double ters_d = param->d * param->d;
const double hcth = param->h - costheta;
const double numerator = -2.0 * ters_c * hcth;
const double denominator = 1.0/(ters_d + hcth*hcth);
return param->gamma*numerator*denominator*denominator;
}
inline double vec3_dot(const double x[3], const double y[3]) const {
return x[0]*y[0] + x[1]*y[1] + x[2]*y[2];
}
inline void vec3_add(const double x[3], const double y[3],
double * const z) const {
z[0] = x[0]+y[0]; z[1] = x[1]+y[1]; z[2] = x[2]+y[2];
}
inline void vec3_scale(const double k, const double x[3],
double y[3]) const {
y[0] = k*x[0]; y[1] = k*x[1]; y[2] = k*x[2];
}
inline void vec3_scaleadd(const double k, const double x[3],
const double y[3], double * const 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
/* ERROR/WARNING messages:
E: Illegal ... command
Self-explanatory. Check the input script syntax and compare to the
documentation for the command. You can use -echo screen as a
command-line option when running LAMMPS to see the offending line.
E: Incorrect args for pair coefficients
Self-explanatory. Check the input script or data file.
E: Pair style Tersoff requires atom IDs
This is a requirement to use the Tersoff potential.
E: Pair style Tersoff requires newton pair on
See the newton command. This is a restriction to use the Tersoff
potential.
E: All pair coeffs are not set
All pair coefficients must be set in the data file or by the
pair_coeff command before running a simulation.
E: Cannot open Tersoff potential file %s
The specified potential file cannot be opened. Check that the path
and name are correct.
E: Incorrect format in Tersoff potential file
Incorrect number of words per line in the potential file.
E: Illegal Tersoff parameter
One or more of the coefficients defined in the potential file is
invalid.
E: Potential file has duplicate entry
The potential file has more than one entry for the same element.
E: Potential file is missing an entry
The potential file does not have a needed entry.
*/

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