问题 I'm trying to to compute pressure tensor of a crystal structure. To do so, I have to go throught all pair of particle like in the simplify code below do i=1, atom_number ! sum over atoms i type1 = ATOMS(i) do nj=POINT(i), POINT(i+1)-1 ! sum over atoms j of i's atoms list j = LIST(nj) type2 = ATOMS(j) call get_ff_param(type1,type2,Aab,Bab,Cab,Dab) call distance_sqr2(i,j,r,VECT_R) call gettensor_rij(i,j,T) r = sqrt(r) if (r<coub_cutoff) then local_sum_real(id+1) = local_sum_real(id+1) + ( erfc