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 problem in excited electronic states has been devised. Calculations of the vibrational structure of polyatomic molecule electronic spectra are performed generally in the adiabatic approximation without invoking additional restrictions. Consecutively taking into account the effects determined by the shift of the potential surface and mixing of normal coordinates by excitation underlies this method. Also the matrix perturbation theory is used. In this method it is possible to use the obtained simple analytic expressions and recurrent relations to compute the overlap integrals. Therefore there is no need to diagonalize a variational matrix of enormous dimensions. The method is well suited for program realization and is highly efficient for calculations of complicated polyatomic molecules.