A METHOD FOR CALCULATING VIBRATIONAL BOUND-STATES - ITERATIVE SOLUTION OF THE COLLOCATION EQUATIONS CONSTRUCTED FROM LOCALIZED BASIS-SETS

We propose a simple and efficient method for calculating vibrational bound states of molecular systems. The technique is based upon iterative solution of the collocation equations. A localized basis set is used which is very efficient for strongly coupled modes and also leads to a diagonally dominant set of collocation equations. The iterative scheme developed is based upon Davidson's method and takes advantage of this diagonal dominance. The approach is capable of exploiting the efficiency with which the matrix elements are calculated in the collocation method by evaluating the matrix elements as they are required. This combination of techniques should allow the method to be used for systems which have more degrees of freedom than have been treated by conventional methods. © 1990 American Institute of Physics.