PAULI REPULSION AND DISPERSION INTERACTION IN THE SELF-CONSISTENT CRYSTAL-FIELD CONCEPT APPLIED TO THE STRUCTURES OF SOLID HCN

The self-consistent crystal field method to address the structures and lattice energies of molecular crystals reported recently, is complemented by Pauli repulsion and dispersion interaction descriptions. The ad hoc Pauli repulsion description contains a parameter that can be fitted to accurate ab initio calculations or to experiment. The dispersion interaction description, which converges the induced multipole-induced multipole interaction contributions to the lattice energy, is obtained by second-order Moller-Plesset perturbation theory. The formalism is applied to the cold and hot phase structures of solid HCN. Two proposed structures of solid HCN, polar and non-polar, were investigated previously. The present study is able to discriminate unambiguously between the two in favour of the polar structure.