Molecular Orbital Calculations of Vibrational Force Constants. I. Ethylene

As a preliminary to the theoretical evaluation of certain out-of-plane vibrational force constants of benzene, the energy levels and twisting frequency of ethylene are calculated by the method of antisymmetric molecular orbitals, no empirical data being used other than molecular dimensions. The problem is oversimplified to a two-electron one, and yet encouraging results are obtained.