2 HYPOTHETICAL STRUCTURES OF SOLID FCN

A Hartree-Fock-based Self-Consistent Crystal Field (HF-SCCF) method is applied to the structure and lattice energy of solid FCN. This struct ure has not been experimentally determined and hence the present study is the first attempt to do so, either by theory or by experiment. The crystal space groups considered are the polar HCN analog and the non- polar CICN analog. Both crystal structures were varied to minimize the lattice energy and 4.8 kcal/mol and 3.9 kcal/mol were obtained for th e polar and non-polar arrangements, respectively. Comparisons to the o ther cyanogen halide solids, HCN((s)) and HF((s)) are made.