A NEW ALGORITHM FOR THE VARIATIONAL SOLUTION OF THE VIBRONIC PROBLEM FOR POLYATOMIC-MOLECULES

A new effective algorithm for solving the complete vibronic problem by the variational method is proposed. The algorithm reduces the variational matrix by successively including the shift and entanglement of normal coordinates and using recurrent formulas for determining the eigenvectors of the matrix. No additional approximations are used. The method is faster than those used previously by two or more orders of magnitude.