pair_chgtrn.h

#pragma once
#include "math/libfunc.h"
#include "math/switch.h"
#include "seq/seq.h"
 
namespace tinker {
#pragma acc routine seq
template <bool DO_G>
SEQ_CUDA
void pair_chgtrn(real r, real cut, real off, real mscale, real f, real alphai,
   real chgi, real alphak, real chgk, real elambda, e_prec& restrict e, e_prec& restrict de)
{
   f *= mscale;
   real expi = REAL_EXP(-alphai * r);
   real expk = REAL_EXP(-alphak * r);
   e = -chgi * expk - chgk * expi;
   e *= f * elambda;
   if CONSTEXPR (DO_G) {
      de = chgi * expk * alphak + chgk * expi * alphai;
      de *= f * elambda;
   }
   if (r > cut) {
      real taper, dtaper;
      switchTaper5<DO_G>(r, cut, off, taper, dtaper);
      if CONSTEXPR (DO_G) de = e * dtaper + de * taper;
      e *= taper;
   }
}
}