anchor.diff:  real(8), optional, intent(out) :: dcdgu2(*)
   real(8), optional, intent(out) :: dcdgd2(*)
   real(8), optional, intent(out) :: dcdgud(*)
  +#ifdef LIBXC
   ! local variables
   integer nspin,xcf,id,i,k
   real(8) r(2),v(2),sigma(3),vsigma(3)
  
positive.code:  vx,vc,vxup,vxdn,vcup,vcdn,dxdg2,dxdgu2,dxdgd2,dxdgud,dcdg2,dcdgu2,dcdgd2, &
   dcdgud)
  
  #ifdef LIBXC
  
  ! !INPUT/OUTPUT PARAMETERS:
  !   xctype : type of exchange-correlation functional (in,integer(3))
  
negative.code: end subroutine
  
  subroutine xcdata_libxc(xctype,xcdescr,xcspin,xcgrad)
  
  implicit none
  ! arguments
  