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lammps/lib/gpu/lal_charmm_long.cu
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lal_charmm_long.cu
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// **************************************************************************
// charmm_long.cu
// -------------------
// W. Michael Brown (ORNL)
//
// Device code for acceleration of the charmm/coul/long pair style
//
// __________________________________________________________________________
// This file is part of the LAMMPS Accelerator Library (LAMMPS_AL)
// __________________________________________________________________________
//
// begin :
// email : brownw@ornl.gov
// ***************************************************************************/
#ifdef NV_KERNEL
#include "lal_aux_fun1.h"
#ifndef _DOUBLE_DOUBLE
texture<float4> pos_tex;
texture<float> q_tex;
#else
texture<int4,1> pos_tex;
texture<int2> q_tex;
#endif
#else
#define pos_tex x_
#define q_tex q_
#endif
__kernel void k_charmm_long(const __global numtyp4 *restrict x_,
const __global numtyp4 *restrict lj1,
const int lj_types,
const __global numtyp *restrict sp_lj,
const __global int *dev_nbor,
const __global int *dev_packed,
__global acctyp4 *restrict ans,
__global acctyp *restrict engv,
const int eflag, const int vflag, const int inum,
const int nbor_pitch,
const __global numtyp *restrict q_,
const numtyp cut_coulsq, const numtyp qqrd2e,
const numtyp g_ewald, const numtyp denom_lj,
const numtyp cut_bothsq, const numtyp cut_ljsq,
const numtyp cut_lj_innersq, const int t_per_atom) {
int tid, ii, offset;
atom_info(t_per_atom,ii,tid,offset);
acctyp energy=(acctyp)0;
acctyp e_coul=(acctyp)0;
acctyp4 f;
f.x=(acctyp)0; f.y=(acctyp)0; f.z=(acctyp)0;
acctyp virial[6];
for (int i=0; i<6; i++)
virial[i]=(acctyp)0;
if (ii<inum) {
int nbor, nbor_end;
int i, numj;
__local int n_stride;
nbor_info(dev_nbor,dev_packed,nbor_pitch,t_per_atom,ii,offset,i,numj,
n_stride,nbor_end,nbor);
numtyp4 ix; fetch4(ix,i,pos_tex); //x_[i];
numtyp qtmp; fetch(qtmp,i,q_tex);
int itype=ix.w;
for ( ; nbor<nbor_end; nbor+=n_stride) {
int j=dev_packed[nbor];
numtyp factor_lj, factor_coul;
factor_lj = sp_lj[sbmask(j)];
factor_coul = (numtyp)1.0-sp_lj[sbmask(j)+4];
j &= NEIGHMASK;
numtyp4 jx; fetch4(jx,j,pos_tex); //x_[j];
int jtype=jx.w;
// Compute r12
numtyp delx = ix.x-jx.x;
numtyp dely = ix.y-jx.y;
numtyp delz = ix.z-jx.z;
numtyp rsq = delx*delx+dely*dely+delz*delz;
int mtype=itype*lj_types+jtype;
if (rsq<cut_bothsq) {
numtyp r2inv=ucl_recip(rsq);
numtyp forcecoul, force_lj, force, r6inv, prefactor, _erfc, switch1;
if (rsq < cut_ljsq) {
r6inv = r2inv*r2inv*r2inv;
force_lj = factor_lj*r6inv*(lj1[mtype].x*r6inv-lj1[mtype].y);
if (rsq > cut_lj_innersq) {
switch1 = (cut_ljsq-rsq);
numtyp switch2 = (numtyp)12.0*rsq*switch1*(rsq-cut_lj_innersq)/
denom_lj;
switch1 *= switch1;
switch1 *= (cut_ljsq+(numtyp)2.0*rsq-(numtyp)3.0*cut_lj_innersq)/
denom_lj;
switch2 *= r6inv*(lj1[mtype].z*r6inv-lj1[mtype].w);
force_lj = force_lj*switch1+switch2;
}
} else
force_lj = (numtyp)0.0;
if (rsq < cut_coulsq) {
numtyp r = ucl_rsqrt(r2inv);
numtyp grij = g_ewald * r;
numtyp expm2 = ucl_exp(-grij*grij);
numtyp t = ucl_recip((numtyp)1.0 + EWALD_P*grij);
_erfc = t * (A1+t*(A2+t*(A3+t*(A4+t*A5)))) * expm2;
fetch(prefactor,j,q_tex);
prefactor *= qqrd2e * qtmp/r;
forcecoul = prefactor * (_erfc + EWALD_F*grij*expm2-factor_coul);
} else
forcecoul = (numtyp)0.0;
force = (force_lj + forcecoul) * r2inv;
f.x+=delx*force;
f.y+=dely*force;
f.z+=delz*force;
if (eflag>0) {
if (rsq < cut_coulsq)
e_coul += prefactor*(_erfc-factor_coul);
if (rsq < cut_ljsq) {
numtyp e=r6inv*(lj1[mtype].z*r6inv-lj1[mtype].w);
if (rsq > cut_lj_innersq)
e *= switch1;
energy+=factor_lj*e;
}
}
if (vflag>0) {
virial[0] += delx*delx*force;
virial[1] += dely*dely*force;
virial[2] += delz*delz*force;
virial[3] += delx*dely*force;
virial[4] += delx*delz*force;
virial[5] += dely*delz*force;
}
}
} // for nbor
store_answers_q(f,energy,e_coul,virial,ii,inum,tid,t_per_atom,offset,eflag,
vflag,ans,engv);
} // if ii
}
__kernel void k_charmm_long_fast(const __global numtyp4 *restrict x_,
const __global numtyp2 *restrict ljd_in,
const __global numtyp *restrict sp_lj_in,
const __global int *dev_nbor,
const __global int *dev_packed,
__global acctyp4 *restrict ans,
__global acctyp *restrict engv,
const int eflag, const int vflag,
const int inum, const int nbor_pitch,
const __global numtyp *restrict q_,
const numtyp cut_coulsq, const numtyp qqrd2e,
const numtyp g_ewald, const numtyp denom_lj,
const numtyp cut_bothsq, const numtyp cut_ljsq,
const numtyp cut_lj_innersq,
const int t_per_atom) {
int tid, ii, offset;
atom_info(t_per_atom,ii,tid,offset);
__local numtyp2 ljd[MAX_BIO_SHARED_TYPES];
__local numtyp sp_lj[8];
if (tid<8)
sp_lj[tid]=sp_lj_in[tid];
if (tid<MAX_BIO_SHARED_TYPES)
ljd[tid]=ljd_in[tid];
if (tid+BLOCK_BIO_PAIR<MAX_BIO_SHARED_TYPES)
ljd[tid+BLOCK_BIO_PAIR]=ljd_in[tid+BLOCK_BIO_PAIR];
acctyp energy=(acctyp)0;
acctyp e_coul=(acctyp)0;
acctyp4 f;
f.x=(acctyp)0; f.y=(acctyp)0; f.z=(acctyp)0;
acctyp virial[6];
for (int i=0; i<6; i++)
virial[i]=(acctyp)0;
__syncthreads();
if (ii<inum) {
int nbor, nbor_end;
int i, numj;
__local int n_stride;
nbor_info(dev_nbor,dev_packed,nbor_pitch,t_per_atom,ii,offset,i,numj,
n_stride,nbor_end,nbor);
numtyp4 ix; fetch4(ix,i,pos_tex); //x_[i];
numtyp qtmp; fetch(qtmp,i,q_tex);
int itype=ix.w;
for ( ; nbor<nbor_end; nbor+=n_stride) {
int j=dev_packed[nbor];
numtyp factor_lj, factor_coul;
factor_lj = sp_lj[sbmask(j)];
factor_coul = (numtyp)1.0-sp_lj[sbmask(j)+4];
j &= NEIGHMASK;
numtyp4 jx; fetch4(jx,j,pos_tex); //x_[j];
int jtype=jx.w;
// Compute r12
numtyp delx = ix.x-jx.x;
numtyp dely = ix.y-jx.y;
numtyp delz = ix.z-jx.z;
numtyp rsq = delx*delx+dely*dely+delz*delz;
if (rsq<cut_bothsq) {
numtyp r2inv=ucl_recip(rsq);
numtyp forcecoul, force_lj, force, prefactor, _erfc, switch1;
numtyp lj3, lj4;
if (rsq < cut_ljsq) {
numtyp eps = ucl_sqrt(ljd[itype].x*ljd[jtype].x);
numtyp sig6 = (numtyp)0.5 * (ljd[itype].y+ljd[jtype].y);
numtyp sig_r_6 = sig6*sig6*r2inv;
sig_r_6 = sig_r_6*sig_r_6*sig_r_6;
lj4 = (numtyp)4.0*eps*sig_r_6;
lj3 = lj4*sig_r_6;
force_lj = factor_lj*((numtyp)12.0 * lj3 - (numtyp)6.0 * lj4);
if (rsq > cut_lj_innersq) {
switch1 = (cut_ljsq-rsq);
numtyp switch2 = (numtyp)12.0*rsq*switch1*(rsq-cut_lj_innersq)/
denom_lj;
switch1 *= switch1;
switch1 *= (cut_ljsq+(numtyp)2.0*rsq-(numtyp)3.0*cut_lj_innersq)/
denom_lj;
switch2 *= lj3-lj4;
force_lj = force_lj*switch1+switch2;
}
} else
force_lj = (numtyp)0.0;
if (rsq < cut_coulsq) {
numtyp r = ucl_rsqrt(r2inv);
numtyp grij = g_ewald * r;
numtyp expm2 = ucl_exp(-grij*grij);
numtyp t = ucl_recip((numtyp)1.0 + EWALD_P*grij);
_erfc = t * (A1+t*(A2+t*(A3+t*(A4+t*A5)))) * expm2;
fetch(prefactor,j,q_tex);
prefactor *= qqrd2e * qtmp/r;
forcecoul = prefactor * (_erfc + EWALD_F*grij*expm2-factor_coul);
} else
forcecoul = (numtyp)0.0;
force = (force_lj + forcecoul) * r2inv;
f.x+=delx*force;
f.y+=dely*force;
f.z+=delz*force;
if (eflag>0) {
if (rsq < cut_coulsq)
e_coul += prefactor*(_erfc-factor_coul);
if (rsq < cut_ljsq) {
numtyp e=lj3-lj4;
if (rsq > cut_lj_innersq)
e *= switch1;
energy+=factor_lj*e;
}
}
if (vflag>0) {
virial[0] += delx*delx*force;
virial[1] += dely*dely*force;
virial[2] += delz*delz*force;
virial[3] += delx*dely*force;
virial[4] += delx*delz*force;
virial[5] += dely*delz*force;
}
}
} // for nbor
store_answers_q(f,energy,e_coul,virial,ii,inum,tid,t_per_atom,offset,eflag,
vflag,ans,engv);
} // if ii
}
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