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FFParticle.h
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FFParticle.h
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/*******************************************************************************
GPU OPTIMIZED MONTE CARLO (GOMC) 2.31
Copyright (C) 2018 GOMC Group
A copy of the GNU General Public License can be found in the COPYRIGHT.txt
along with this program, also can be found at <http://www.gnu.org/licenses/>.
********************************************************************************/
#ifndef FF_PARTICLE_H
#define FF_PARTICLE_H
#include "EnsemblePreprocessor.h" //For "MIE_INT_ONLY" preprocessor.
#include "FFConst.h" //constants related to particles.
#include "BasicTypes.h" //for uint
#include "NumLib.h" //For Cb, Sq
#include "Setup.h"
#ifdef GOMC_CUDA
#include "VariablesCUDA.cuh"
#endif
// Virial and LJ potential calculation:
// U(rij) = cn * eps_ij * ( (sig_ij/rij)^n - (sig_ij/rij)^6)
//
// cn = n/(n-6) * ((n/6)^(6/(n-6)))
//
// eps_E_cn = cn * eps_ij
// __________const__________________
// U_lrc = density * 0.5 * 4.0 / (n-3) * cn * pi * eps_ij * sig_ij^3 *
// ( (sig_ij/rij)^(n-3) - (n-3)/3*(sig_ij/rij)^3)
//
// Vir(r) = cn * eps_ij * n * (sig_ij/rij)^n - cn * eps_ij * 6 * (sig_ij/rij)^6
// Vir(r) = cn * eps_ij * n * repulse - cn * eps_ij * 6 * attract
// Vir(r) = cn * eps_ij * (n * repulse - 6 * attract)
// Vir(r) = cn * eps_ij * 6 * ((n/6) * repulse - attract)
//
// Vir_lrc = density * 0.5 * 4.0 * 2/3 * cn * pi * eps_ij * sig_ij^3 *
// ( n/(n-3) * 3/2 * (sig_ij/rij)^(n-3) - 3*(sig_ij/rij)^3)
namespace ff_setup
{
class Particle;
class NBfix;
}
namespace config_setup
{
struct SystemVals;
struct FFValues;
struct FFKind;
}
struct FFParticle {
public:
FFParticle();
~FFParticle(void);
double GetMass(const uint kind) const
{
return mass[kind];
}
double GetEpsilon(const uint i, const uint j) const;
double GetEpsilon_1_4(const uint i, const uint j) const;
double GetSigma(const uint i, const uint j) const;
double GetSigma_1_4(const uint i, const uint j) const;
double GetN(const uint i, const uint j) const;
double GetN_1_4(const uint i, const uint j) const;
// LJ interaction functions
virtual double CalcEn(const double distSq,
const uint kind1, const uint kind2) const;
virtual double CalcVir(const double distSq,
const uint kind1, const uint kind2) const;
virtual void CalcAdd_1_4(double& en, const double distSq,
const uint kind1, const uint kind2) const;
// coulomb interaction functions
virtual double CalcCoulomb(const double distSq,
const double qi_qj_Fact) const;
virtual double CalcCoulombEn(const double distSq,
const double qi_qj_Fact) const;
virtual double CalcCoulombVir(const double distSq,
const double qi_qj) const;
virtual void CalcCoulombAdd_1_4(double& en, const double distSq,
const double qi_qj_Fact,
const bool NB) const;
void Init(ff_setup::Particle const& mie,
ff_setup::NBfix const& nbfix,
config_setup::SystemVals const& sys,
config_setup::FFKind const& ffKind);
//!Returns Energy long-range correction term for a kind pair
virtual double EnergyLRC(const uint kind1, const uint kind2) const;
//!Returns Energy long-range correction term for a kind pair
virtual double VirialLRC(const uint kind1, const uint kind2) const;
uint NumKinds() const
{
return count;
}
#ifdef GOMC_CUDA
VariablesCUDA *getCUDAVars()
{
return varCUDA;
}
#endif
protected:
uint FlatIndex(const uint i, const uint j) const
{
return i + j * count;
}
void Blend(ff_setup::Particle const& mie, const double rCut);
void AdjNBfix(ff_setup::Particle const& mie, ff_setup::NBfix const& nbfix,
const double rCut);
//vars for lj particles.
double* mass;
std::string *nameFirst;
std::string *nameSec;
//vars for LJ-LJ pairs
#ifdef MIE_INT_ONLY
uint* n, *n_1_4;
#else
double *n, *n_1_4;
#endif
//For LJ eps_cn(en) --> 4eps, eps_cn_6 --> 24eps, eps_cn_n --> 48eps
double * sigmaSq, * epsilon, * epsilon_1_4, * epsilon_cn, * epsilon_cn_6,
* nOver6, * sigmaSq_1_4, * epsilon_cn_1_4, * epsilon_cn_6_1_4, * nOver6_1_4,
* enCorrection, * virCorrection, *shiftConst, *An, *Bn, *Cn, *sig6,
*sign, *shiftConst_1_4, *An_1_4, *Bn_1_4, *Cn_1_4, *sig6_1_4, *sign_1_4;
double rCut, rCutSq, rOn, rOnSq, rOnCoul, A1, B1, C1, A6, B6, C6,
factor1, factor2, scaling_14, alpha, diElectric_1;
double rCutLow, rCutLowSq;
uint count, vdwKind;
bool isMartini, ewald;
#ifdef GOMC_CUDA
VariablesCUDA *varCUDA;
#endif
};
inline void FFParticle::CalcAdd_1_4(double& en, const double distSq,
const uint kind1, const uint kind2) const
{
uint index = FlatIndex(kind1, kind2);
double rRat2 = sigmaSq_1_4[index] / distSq;
double rRat4 = rRat2 * rRat2;
double attract = rRat4 * rRat2;
#ifdef MIE_INT_ONLY
uint n_ij = n_1_4[index];
double repulse = num::POW(rRat2, rRat4, attract, n_ij);
#else
double n_ij = n_1_4[index];
double repulse = pow(sqrt(rRat2), n_ij);
#endif
en += epsilon_cn_1_4[index] * (repulse - attract);
}
inline void FFParticle::CalcCoulombAdd_1_4(double& en, const double distSq,
const double qi_qj_Fact,
const bool NB) const
{
double dist = sqrt(distSq);
if(NB)
en += qi_qj_Fact / dist;
else
en += qi_qj_Fact * scaling_14 / dist;
}
//mie potential
inline double FFParticle::CalcEn(const double distSq,
const uint kind1, const uint kind2) const
{
uint index = FlatIndex(kind1, kind2);
double rRat2 = sigmaSq[index] / distSq;
double rRat4 = rRat2 * rRat2;
double attract = rRat4 * rRat2;
#ifdef MIE_INT_ONLY
uint n_ij = n[index];
double repulse = num::POW(rRat2, rRat4, attract, n_ij);
#else
double n_ij = n[index];
double repulse = pow(sqrt(rRat2), n_ij);
#endif
return epsilon_cn[index] * (repulse - attract);
}
inline double FFParticle::CalcCoulomb(const double distSq,
const double qi_qj_Fact) const
{
if(ewald) {
double dist = sqrt(distSq);
double val = alpha * dist;
return qi_qj_Fact * erfc(val) / dist;
} else {
double dist = sqrt(distSq);
return qi_qj_Fact / dist;
}
}
//will be used in energy calculation after each move
inline double FFParticle::CalcCoulombEn(const double distSq,
const double qi_qj_Fact) const
{
if(distSq <= rCutLowSq)
return num::BIGNUM;
if(ewald) {
double dist = sqrt(distSq);
double val = alpha * dist;
return qi_qj_Fact * erfc(val) / dist;
} else {
double dist = sqrt(distSq);
return qi_qj_Fact / dist;
}
}
inline double FFParticle::CalcVir(const double distSq,
const uint kind1, const uint kind2) const
{
uint index = FlatIndex(kind1, kind2);
double rNeg2 = 1.0 / distSq;
double rRat2 = rNeg2 * sigmaSq[index];
double rRat4 = rRat2 * rRat2;
double attract = rRat4 * rRat2;
#ifdef MIE_INT_ONLY
uint n_ij = n[index];
double repulse = num::POW(rRat2, rRat4, attract, n_ij);
#else
double n_ij = n[index];
double repulse = pow(sqrt(rRat2), n_ij);
#endif
//Virial is the derivative of the pressure... mu
return epsilon_cn_6[index] * (nOver6[index] * repulse - attract) * rNeg2;
}
inline double FFParticle::CalcCoulombVir(const double distSq,
const double qi_qj) const
{
if(ewald) {
double dist = sqrt(distSq);
double constValue = 2.0 * alpha / sqrt(M_PI);
double expConstValue = exp(-1.0 * alpha * alpha * distSq);
double temp = 1.0 - erf(alpha * dist);
return qi_qj * (temp / dist + constValue * expConstValue) / distSq;
} else {
double dist = sqrt(distSq);
return qi_qj / (distSq * dist);
}
}
#endif /*FF_PARTICLE_H*/