Determination of the intermolecular potential energy surface for (HCl)2 from vibration—rotation—tunneling spectroscopy
An accurate and detailed semiempirical intermolecular potential energy surface for (HCl)2 has been determined by a direct nonlinear least-squares fit to 33 microwave, far-infrared and near-infrared spectroscopic quantities using the analytical potential model of Bunker et al. [J. Mol. Spectrosc. 146, 200 (1991)] and a rigorous four-dimensional dynamical method (described in the accompanying paper). The global minimum (De=-692 cm-1) is located near the hydrogen-bonded L-shaped geometry (R=3.746 A-ring, theta 1=9°, theta 2=89.8°, and &fgr;=180°). The marked influence of anisotropic repulsive forces is evidenced in the radial dependence of the donor—acceptor interchange tunneling pathway. The minimum energy pathway in this low barrier (48 cm-1) process involves a contraction of 0.1 A-ring in the center of mass distance (R) at the C2h symmetry barrier position. The new surface is much more accurate than either the ab initio formulation of Bunker et al. or a previous semiempirical surface [J. Chem. Phys. 78, 6841 (1983)].
Elrod, M.J., and R.J. Saykally. 1995. "Determination of the Intermolecular Potential Energy Surface for (HCl)2 from Vibration—Rotation—Tunneling Spectroscopy." Journal of Chemical Physics 103: 933.
Journal of Chemical Physics
Chemistry and Biochemistry
Hydrochloric acid, Potential energy surfaces, Vibrational states, Rotational states, Intermolecular forces, Hydrogen bonds, Tunneling, Least square fit