Ten years of experience in polymorph prediction: what next?

Several issues in the computational prediction of polymorphic crystal structures are examined; the enthalpyforce field issue, the intra-intermolecular energy issue, the entropy issue, the temperature issue, the kinetic energy issue, and the kinetic-dynamic issue. Perspectives in the derivation of an absolute force field, based soley on molecular electron densities, are examined, together with its possible application to static and dynamic calculations, with an estimate of the investment and computational costs.