Potential Energy Surface for Dispersion Interaction in (H2O)2 and (HF)2
Journal of Physical Chemistry
The nonexpanded second-order dispersion energy is calculated for a number of geometrical configurations of ( H20)2 and (HF), within the framework of Sadlej’s “medium-polarized” basis sets. This treatment closely reproduces current benchmarks for the water dimer. In addition to monitoring the behavior of the dispersion energy as the proton donor and acceptor water molecule are misoriented from the linear geometry, this work examines a number of other structures such as the cyclic, stacked, and bifurcated dimers. The dispersion energy is shown to be highly anisotropic, generally favoring orientations that best allow overlap between occupied MOs of the two subunits; H-bonded geometries are favored over other structures. The computed dispersion energies of (H20), and (HF), are fit to an analytical potential involving isotropic atom-atom parameters. A model that combines UHwFith dispersion energy does not correctly reproduce the radial and angular dependence of the interaction energy when compared to Mdler-Plesset perturbation theory results.
Potential Energy Surface for Dispersion Interaction in (H2O)2 and (HF)2 M. M. Szczesniak, R. J. Brenstein, S. M. Cybulski, S. Scheiner J. Phys. Chem. 1990 94, 1781-1788.