1 /* ----------------------------------------------------------------------
2 LAMMPS - Large-scale Atomic/Molecular Massively Parallel Simulator
3
4 Original Version:
5 http://lammps.sandia.gov, Sandia National Laboratories
6 Steve Plimpton, sjplimp@sandia.gov
7
8 See the README file in the top-level LAMMPS directory.
9
10 -----------------------------------------------------------------------
11
12 USER-CUDA Package and associated modifications:
13 https://sourceforge.net/projects/lammpscuda/
14
15 Christian Trott, christian.trott@tu-ilmenau.de
16 Lars Winterfeld, lars.winterfeld@tu-ilmenau.de
17 Theoretical Physics II, University of Technology Ilmenau, Germany
18
19 See the README file in the USER-CUDA directory.
20
21 This software is distributed under the GNU General Public License.
22 ------------------------------------------------------------------------- */
23
PairLJGromacsCuda_Eval(const F_FLOAT & rsq,const int ij_type,F_FLOAT & factor_lj,int & eflag,ENERGY_FLOAT & evdwl)24 __device__ inline F_FLOAT PairLJGromacsCuda_Eval(const F_FLOAT &rsq, const int ij_type, F_FLOAT &factor_lj, int &eflag, ENERGY_FLOAT &evdwl)
25 {
26 F_FLOAT tlj;
27 const F_FLOAT r2inv = F_F(1.0) / rsq;
28 const F_FLOAT r = _RSQRT_(r2inv);
29 const F_FLOAT r6inv = r2inv * r2inv * r2inv;
30 F_FLOAT forcelj = r6inv * (_lj1[ij_type] * r6inv - _lj2[ij_type]);
31 const X_FLOAT cut_lj_innersq = (_cut_innersq_global > X_F(0.0) ? _cut_innersq_global : _cut_innersq[ij_type]);
32
33 if(rsq > cut_lj_innersq) {
34 tlj = r - _SQRT_(cut_lj_innersq);
35 forcelj += r * tlj * tlj * (_ljsw1[ij_type] + _ljsw2[ij_type] * tlj);
36 }
37
38 if(eflag) {
39 ENERGY_FLOAT evdwl_tmp = r6inv * (_lj3[ij_type] * r6inv - _lj4[ij_type]);
40
41 if(rsq > cut_lj_innersq) {
42 evdwl_tmp += tlj * tlj * tlj *
43 (_ljsw3[ij_type] + _ljsw4[ij_type] * tlj) + _ljsw5[ij_type];;
44 }
45
46 evdwl += evdwl_tmp * factor_lj;
47 }
48
49 return factor_lj * forcelj * r2inv;
50 }
51