subroutine p(x, r)
include 'particle-FF-adifor.inc'
double precision x(dims), r, charge(dims), s
double precision charges(ncharges, dims)
common /closure/ charges
integer k, l
r = 0d0
do l = 1, ncharges
do k = 1, dims
charge(k) = charges(l, k)
enddo
call distance(dims, x, charge, s)
r = r+1d0/s
enddo
end