Comparison between the classical interaction energy and periodic Hartree-Fock binding energies for the interaction between molecules and surfaces

Conference · Fri Dec 01 04:00:00 EST 1995

OSTI ID:126868

Chacon-Taylor, M R; McCarthy, M I ^[1]

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1. Pacific Northwest Lab., Richland, WA (United States)

A classical interaction energy model was compared to the ab initio periodic Hartree-Fock LCAO method for the energetics of the H{sub 2}O, HCl, and NH{sub 3}/MgO(001) interface. The QM calculations treated a system that was periodic in two dimensions with the adsorbate approaching a three-layer slab of MgO(001). This classical interaction energy model describes the surface by its potential, electric field, and electric field derivatives at the position of the molecule center of mass, and the molecule by its charge, electric dipole, electric quadrupole, and polarizability. The potential, electric field, and electric-field gradient are obtained for the clean three-layer slab using the ab initio periodic Hartree-Fock LCAO method. The charge, electric dipole, electric quadrupole, and polarizability are calculated using ab initio, Hartree-Fock theory. An e(s/r)-12 repulsive potential is added to the classical interaction energy to obtain binding energies and equilibrium distances. Using the covalent radius to estimate the size of the adsorbate leads to binding energies within 1 kcal/mol of the periodic Hartree-Fock values, except for hydrogen bonded configurations that are underestimated by about 4.5 kcal/mol.

• OSTI ID: 126868
• Report Number(s): CONF-950402--
• Country of Publication: United States
• Language: English

Related Subjects

40 CHEMISTRY
ADSORPTION
AMMONIA
BINDING ENERGY
EQUILIBRIUM
HYDROCHLORIC ACID
HYDROGEN
LCAO METHOD
MAGNESIUM OXIDES
MOLECULES
POLARIZABILITY
SURFACE PROPERTIES
WATER