On one hand, comparative molecular surface analysis (CoMFA) implies calculations of eld values on the numerous nodes of the lattice. On the other hand, the expression chosen for the potentials is not without problems. Lennard-Jones potentials are very steep near the atomic positions. Hence, the need for very precise alignment rules (a small variation in position leading to largely different values of the steric eld) and the choice, in order to treat simultaneously the steric and electrostatic components, of (somewhat arbitrary) scaling factors, which leads to some information loss. As a consequence, contour maps sometimes present singularities, making their interpretation unclear. Furthermore, limiting structural inšuences to steric and electrostatic contributions may seem a rather crude approximation (although introduction in CoMFA of additional variables and other elds was proposed).