ROTATIONAL RESONANCE STATES OF AR-HCL(V=0) BY FINITE-RANGE SCATTERINGWAVE-FUNCTION METHOD

The low lying rotational resonance states of Ar-HCl van der Waals mole cule in the vibrational ground state of HCl are calculated for several total angular momentum states within the model of a rigid rotor-atom system. The necessary scattering calculations are done by the finite r ange scattering wave function (FRSW) method [J. Chem. Phys. 99, 1057 ( 1993)] adopting energy independent auxiliary functions which makes the scattering calculations at many energies much more efficient. Discret e eigenvectors and eigenvalues of Hamiltonian matrix are calculated on a finite range via the successive diagonalization-truncation scheme c ombined with the discrete variable representation (DVR). Analytical ei genfunctions of the asymptotic Hamiltonian operator in a body-fixed fr ame excluding only the interaction potential, but including all the ef fective centrifugal potential terms, are used as asymptotic wave funct ions, which reduces the dynamical range required for the L(2) scatteri ng calculations. After a single diagonalization of the Hamiltonian in the finite range L(2) representation, resonance parameters are extract ed through the energy dependence of Smith's lifetime matrix. A search algorithm for multiple resonances is used assuming constant background effects and isolated, simple resonances. Several recommendations for the choice of the translational basis functions and the basis set rang es which target specific kinds of resonances with various accuracies a re given. Resonance energies and widths (lifetimes and partial decay p robabilities) for many predissociating states of Ar-HCl are given with unprecedental accuracy.