NONREACTIVE ATOM MOLECULE-SURFACE SCATTERING WITHIN THE FINITE BASIS WAVE-PACKET METHOD/

A quantum wave packet code for studying nonreactive scattering of clos ed-shell atoms or diatomic molecules from a rigid surface is described , The time evolution relies on the Chebychev propagator. Up to 5 colli der degrees of freedom, 3 in translation and 2 in rotation, are treate d in a pseudospectral way with the momentum or finite basis representa tion as the primary space. Potential matrix elements are efficiently e valuated by means of sequential 1D transformations between momentum an d coordinate spaces. Fast Fourier transforms are performed for the tra nslational and azimuthal coordinates whereas a Gauss-Legendre transfor m is used for the polar coordinate. This pseudospectral strategy minim izes memory requirements because no off-diagonal Hamiltonian matrix el ements need to be stored, In addition, a wide variety of physical syst ems can be studied since no particular functional form is imposed for the interaction potential.