Why is the area under X(e)...H(i) different from that under H(e)...X(i) in Hirshfeld Surface area calculation (Crystal Explorer)? Should they not be same? I want to know in the case of one or less number of molecule in the asymmetric unit. For example H(i)...O(e) = 16.0% and O(i)...H(e) = 12.6% in the case of methanol (i=internal or inside and e=external or outside). Now if H(e) comes into contact with O(i), same amount of area (= 12.6 %) on H(e) as well as O(i) are involved. Because there is only one molecule in the asymmetric unit, external hydrogen and internal hydrogen behave in same manner, i.e. 12.6% of H(i) also should be involved not 16%.