METHODS FOR CALCULATION OF ELECTRONIC VIBRATIONAL-SPECTRA OF POLYATOMIC-MOLECULES .2. VARIATIONAL SOLUTION OF THE ELECTRONIC VIBRATIONAL PROBLEM

A more refined method for variational solution of the vibrational prob lem in excited electronic states has been devised. Calculations of the vibrational structure of polyatomic molecule electronic spectra are p erformed generally in the adiabatic approximation without invoking add itional restrictions. Consecutively taking into account the effects de termined by the shift of the potential surface and mixing of normal co ordinates by excitation underlies this method. Also the matrix perturb ation theory is used. In this method it is possible to use the obtaine d simple analytic expressions and recurrent relations to compute the o verlap integrals. Therefore there is no need to diagonalize a variatio nal matrix of enormous dimensions. The method is well suited for progr am realization and is highly efficient for calculations of complicated polyatomic molecules.