Computation of rovibrational eigenvalues of van der Waals molecules on a CRAY T3D

This report discusses two algorithms for calculating the rotational and vibrational states of Van der Waals molecules on a Cray T3D 128 multiprocessor computer. Both of these algorithms utilize a discreter variable representation (DVR) of the rovibrational Hamiltonians for the test molecule Ar-HO. Algorithm number one, applies the restarted Lanczos method (IRLM) directly to the DVR Hamiltonians to obtain the eigenpairs. Algorithm number two, uses the sequential diagonalization and trunction (SDT) approach to transforms the DVR Hamiltonian to a reduced order SDT Hamiltonian before applying IRLM