A series of variational calculations are reported for the ethylene molecule, using ASMO LCAO method with CGTO's (combined Gaussian-type orbitals) as the basic atomic orbitals. The three electronic states, 1Ag(N), 3B1 u(T) and 1B1 u(V), are investigated with a special emphasis on the 1B1u state. © 1969 Springer-Verlag.