Molecular Orbital Theory for Infinite Systems: Hydrogen-Bonded Molecular Crystals

In a previous paper a self consistent field (SCF) perturbation theory of the interaction between two molecules of a dimer was given. We now extend this theory to molecular crystals, with special reference to hydrogen bonded systems. The theory derived is used to calculate the geometry and energy for an infinite chain of HF molecules. The theory is checked by comparing the results obtained from some direct CNDO calculations. Calculations are reported for the three dimensional HF crystal also. According to CNDO theory, the nonpolar structure is the more stable by 2 kcal/mole.