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lammps/lib/gpu/lal_lj_cubic.cu

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// **************************************************************************
// lj_cubic.cu
// -------------------
// Trung Dac Nguyen
//
// Device code for acceleration of the lj/cubic pair style
//
// __________________________________________________________________________
// This file is part of the LAMMPS Accelerator Library (LAMMPS_AL)
// __________________________________________________________________________
//
// begin :
// email : ndactrung@gmail.com
// ***************************************************************************/
#ifdef NV_KERNEL
#include "lal_aux_fun1.h"
#ifndef _DOUBLE_DOUBLE
texture<float4> pos_tex;
#else
texture<int4,1> pos_tex;
#endif
#else
#define pos_tex x_
#endif
// LJ quantities scaled by epsilon and rmin = sigma*2^1/6 (see src/pair_lj_cubic.h)
#define _RT6TWO (numtyp)1.1224621
#define _PHIS (numtyp)-0.7869823 /* energy at s */
#define _DPHIDS (numtyp)2.6899009 /* gradient at s */
#define _A3 (numtyp)27.93357 /* cubic coefficient */
__kernel void k_lj_cubic(const __global numtyp4 *restrict x_,
const __global numtyp4 *restrict lj1,
const __global numtyp4 *restrict lj2,
const __global numtyp2 *restrict lj3,
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 int t_per_atom) {
int tid, ii, offset;
atom_info(t_per_atom,ii,tid,offset);
acctyp energy=(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 i, numj, nbor, nbor_end;
__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];
int itype=ix.w;
numtyp factor_lj;
for ( ; nbor<nbor_end; nbor+=n_stride) {
int j=dev_packed[nbor];
factor_lj = sp_lj[sbmask(j)];
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<lj1[mtype].z) {
numtyp r2inv,r6inv,force,t;
r2inv=ucl_recip(rsq);
if (rsq <= lj2[mtype].x) {
r6inv = r2inv*r2inv*r2inv;
force = r6inv * (lj1[mtype].x*r6inv - lj1[mtype].y);
} else {
numtyp r = ucl_sqrt(rsq);
numtyp rmin = lj2[mtype].z*_RT6TWO;
t = (r - lj2[mtype].y)/rmin;
force = lj2[mtype].w*(-_DPHIDS + _A3*t*t/2.0)*r/rmin;
}
force*=factor_lj*r2inv;
f.x+=delx*force;
f.y+=dely*force;
f.z+=delz*force;
if (eflag>0) {
numtyp e;
if (rsq <= lj2[mtype].x)
e = r6inv*(lj3[mtype].x*r6inv-lj3[mtype].y);
else
e = lj2[mtype].w*(_PHIS + _DPHIDS*t - _A3*t*t*t/6.0);
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(f,energy,virial,ii,inum,tid,t_per_atom,offset,eflag,vflag,
ans,engv);
} // if ii
}
__kernel void k_lj_cubic_fast(const __global numtyp4 *restrict x_,
const __global numtyp4 *restrict lj1_in,
const __global numtyp4 *restrict lj2_in,
const __global numtyp2 *restrict lj3_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 int t_per_atom) {
int tid, ii, offset;
atom_info(t_per_atom,ii,tid,offset);
__local numtyp4 lj1[MAX_SHARED_TYPES*MAX_SHARED_TYPES];
__local numtyp4 lj2[MAX_SHARED_TYPES*MAX_SHARED_TYPES];
__local numtyp2 lj3[MAX_SHARED_TYPES*MAX_SHARED_TYPES];
__local numtyp sp_lj[4];
if (tid<4)
sp_lj[tid]=sp_lj_in[tid];
if (tid<MAX_SHARED_TYPES*MAX_SHARED_TYPES) {
lj1[tid]=lj1_in[tid];
lj2[tid]=lj2_in[tid];
if (eflag>0)
lj3[tid]=lj3_in[tid];
}
acctyp energy=(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 i, numj, nbor, nbor_end;
__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];
int iw=ix.w;
int itype=fast_mul((int)MAX_SHARED_TYPES,iw);
numtyp factor_lj;
for ( ; nbor<nbor_end; nbor+=n_stride) {
int j=dev_packed[nbor];
factor_lj = sp_lj[sbmask(j)];
j &= NEIGHMASK;
numtyp4 jx; fetch4(jx,j,pos_tex); //x_[j];
int mtype=itype+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<lj1[mtype].z) {
numtyp r2inv,r6inv,force,t;
r2inv=ucl_recip(rsq);
if (rsq <= lj2[mtype].x) {
r6inv = r2inv*r2inv*r2inv;
force = r6inv * (lj1[mtype].x*r6inv - lj1[mtype].y);
} else {
numtyp r = ucl_sqrt(rsq);
numtyp rmin = lj2[mtype].z*_RT6TWO;
t = (r - lj2[mtype].y)/rmin;
force = lj2[mtype].w*(-_DPHIDS + _A3*t*t/2.0)*r/rmin;
}
force*=factor_lj*r2inv;
f.x+=delx*force;
f.y+=dely*force;
f.z+=delz*force;
if (eflag>0) {
numtyp e;
if (rsq <= lj2[mtype].x)
e = r6inv*(lj3[mtype].x*r6inv-lj3[mtype].y);
else
e = lj2[mtype].w*(_PHIS + _DPHIDS*t - _A3*t*t*t/6.0);
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(f,energy,virial,ii,inum,tid,t_per_atom,offset,eflag,vflag,
ans,engv);
} // if ii
}
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