fix factor 0.5 bug in lj/charmm/coul/charmm/implicit/omp

      dely = ytmp - x[j].y;

      delz = ztmp - x[j].z;

      rsq = delx*delx + dely*dely + delz*delz;

      jtype = type[j];

      if (rsq < cut_bothsq) {

        r2inv = 1.0/rsq;

              (cut_coulsq + 2.0*rsq - 3.0*cut_coul_innersq) * invdenom_coul;

            switch2 = 12.0*rsq * (cut_coulsq-rsq) *

              (rsq-cut_coul_innersq) * invdenom_coul;

            forcecoul *= switch1 + switch2;

            forcecoul *= switch1 + 0.5*switch2;

          }

          forcecoul *= factor_coul;

        } else forcecoul = 0.0;