fac=-expon*(e1+evdwij)*rij_shift
sigder=fac*sigder
fac=rij*fac
- fac=fac+evdwij/(1.0-sss)*(-sssgrad)/sigmaii(itypi,itypj)*rij
+ fac=fac+evdwij/sss*(-sssgrad)/sigmaii(itypi,itypj)*rij
c fac=0.0d0
C Calculate the radial part of the gradient
gg(1)=xj*fac