# Quantum vibrational eigenstates from classical origins

## Description

Abstract An efficient method for obtaining molecular vibrational eigenstates using a basis set made up of semiclassical eigenstates is presented. The semiclassical basis functions are constructed from a set of Gaussian functions distributed uniformly on the invariant N-torus defined by a single quasiperiodic classical trajectory. A uniform distribution of Gaussians is achieved by mapping a uniform grid of points in the Hamilton-Jacobi angle variables (which parametrize the surface of the N-torus) onto... Title of program: DEMETER Catalogue Id: ABDM_v1_0 Nature of problem DETMETER uses output from PANDORA to construct a specified quantum mechanical basis set from semiclassical eigenstates and diagonalizes. Command input at runtime is used to control (i) which semiclassical functions will be included in the basis, (ii) whether or not eigenvectors will be computed and stored, and (iii) whether or not the Hamiltonian and overlap matrices are stored for subsequent calculations. Versions of this program held in the CPC repository in Mendeley Data abdm_v1_0; DEMETER; 10.1016/0010-4655(88)90064-1 This program has been imported from the CPC Program Library held at Queen's University Belfast (1969-2019)