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lammps/lib/gpu/lal_zbl.cu

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// **************************************************************************
// zbl.cu
// -------------------
// Trung Dac Nguyen
//
// Device code for acceleration of the zbl 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
// ZBL constants
#define c1 (numtyp)0.02817
#define c2 (numtyp)0.28022
#define c3 (numtyp)0.50986
#define c4 (numtyp)0.18175
/* ----------------------------------------------------------------------
compute ZBL pair energy
------------------------------------------------------------------------- */
ucl_inline numtyp e_zbl(numtyp r, numtyp d1aij, numtyp d2aij,
numtyp d3aij, numtyp d4aij, numtyp zzeij) {
numtyp rinv = ucl_recip(r);
numtyp sum = c1*ucl_exp(-d1aij*r);
sum += c2*ucl_exp(-d2aij*r);
sum += c3*ucl_exp(-d3aij*r);
sum += c4*ucl_exp(-d4aij*r);
numtyp result = zzeij*sum*rinv;
return result;
};
/* ----------------------------------------------------------------------
compute ZBL first derivative
------------------------------------------------------------------------- */
ucl_inline numtyp dzbldr(numtyp r, numtyp d1aij, numtyp d2aij,
numtyp d3aij, numtyp d4aij, numtyp zzeij) {
numtyp rinv = ucl_recip(r);
numtyp e1 = ucl_exp(-d1aij*r);
numtyp e2 = ucl_exp(-d2aij*r);
numtyp e3 = ucl_exp(-d3aij*r);
numtyp e4 = ucl_exp(-d4aij*r);
numtyp sum = c1*e1;
sum += c2*e2;
sum += c3*e3;
sum += c4*e4;
numtyp sum_p = -c1*d1aij*e1;
sum_p -= c2*d2aij*e2;
sum_p -= c3*d3aij*e3;
sum_p -= c4*d4aij*e4;
numtyp result = zzeij*(sum_p - sum*rinv)*rinv;
return result;
};
__kernel void k_zbl(const __global numtyp4 *restrict x_,
const __global numtyp4 *restrict coeff1,
const __global numtyp4 *restrict coeff2,
const __global numtyp4 *restrict coeff3,
const double cut_globalsq,
const double cut_innersq,
const double cut_inner,
const int lj_types,
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 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];
int itype=ix.w;
for ( ; nbor<nbor_end; nbor+=n_stride) {
int j=dev_packed[nbor];
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_globalsq) {
numtyp r, t, force;
r = ucl_sqrt(rsq);
force = dzbldr(r, coeff2[mtype].x, coeff2[mtype].y,
coeff2[mtype].z, coeff2[mtype].w, coeff1[mtype].z);
if (rsq>cut_innersq) {
t = r - cut_inner;
force = t*t * (coeff1[mtype].x + coeff1[mtype].y*t);
}
force *= (numtyp)-1.0*ucl_recip(r);
f.x+=delx*force;
f.y+=dely*force;
f.z+=delz*force;
if (eflag>0) {
numtyp e=e_zbl(r, coeff2[mtype].x, coeff2[mtype].y,
coeff2[mtype].z, coeff2[mtype].w, coeff1[mtype].z);
e += coeff3[mtype].z;
if (rsq > cut_innersq) {
e += t*t*t * (coeff3[mtype].x + coeff3[mtype].y*t);
}
energy+=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_zbl_fast(const __global numtyp4 *restrict x_,
const __global numtyp4 *restrict coeff1_in,
const __global numtyp4 *restrict coeff2_in,
const __global numtyp4 *restrict coeff3_in,
const double cut_globalsq,
const double cut_innersq,
const double cut_inner,
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 coeff1[MAX_SHARED_TYPES*MAX_SHARED_TYPES];
__local numtyp4 coeff2[MAX_SHARED_TYPES*MAX_SHARED_TYPES];
__local numtyp4 coeff3[MAX_SHARED_TYPES*MAX_SHARED_TYPES];
if (tid<MAX_SHARED_TYPES*MAX_SHARED_TYPES) {
coeff1[tid]=coeff1_in[tid];
coeff2[tid]=coeff2_in[tid];
coeff3[tid]=coeff3_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 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];
int iw=ix.w;
int itype=fast_mul((int)MAX_SHARED_TYPES,iw);
for ( ; nbor<nbor_end; nbor+=n_stride) {
int j=dev_packed[nbor];
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<cut_globalsq) {
numtyp r, t, force;
r = ucl_sqrt(rsq);
force = dzbldr(r, coeff2[mtype].x, coeff2[mtype].y,
coeff2[mtype].z, coeff2[mtype].w, coeff1[mtype].z);
if (rsq>cut_innersq) {
t = r - cut_inner;
force += t*t * (coeff1[mtype].x + coeff1[mtype].y*t);
}
force *= (numtyp)-1.0*ucl_recip(r);
f.x+=delx*force;
f.y+=dely*force;
f.z+=delz*force;
if (eflag>0) {
numtyp e=e_zbl(r, coeff2[mtype].x, coeff2[mtype].y,
coeff2[mtype].z, coeff2[mtype].w, coeff1[mtype].z);
e += coeff3[mtype].z;
if (rsq > cut_innersq) {
e += t*t*t * (coeff3[mtype].x + coeff3[mtype].y*t);
}
energy+=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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