AN ABINITIO STUDY OF THE HYDROGEN-CHLORIDE DIMER - THE POTENTIAL-ENERGY SURFACE AND THE CHARACTERIZATION OF THE STATIONARY-POINTS

The potential energy surface of the hydrogen chloride dimer has been investigated within the framework of the averaged coupled pair functional (ACPF) approach applying two extended, polarized basis sets. With the larger basis set which includes f functions, 606 individual points have been computed, mainly for planar configurations, whereas with the smaller basis set 1654 points, among them a substantial number of non-planar geometries, have been evaluated on the 6D energy surface. The characteristic features of the potential energy surface are discussed with the aid of a series of contour plots for various selected 2D cuts through the energy surface, and a detailed comparison to the related case of the hydrogen fluoride dimer is given. Several stationary points have been located and optimized structural parameters for these are reported. For the more important ones, those that determine the shape of the minimum energy path of the spectroscopically observable trans-bending tunneling motion, harmonic vibrational frequencies are reported as well. This minimum energy path differs qualitatively from that in the hydrogen fluoride dimer.