Quantum Mechanics in Gas Crystal-Surface Van Der Waals Scattering

Abstract

Publisher Summary The theory of two-particle interactions divides the domain of nuclear separation into two regions. The parameters of the interaction energy function are the properties of the isolated particles: charge, electric and magnetic dipole moments, quadrupole moments, polarizability, characteristic frequencies, and optical transition probabilities. Where gas molecules have a permanent electric quadrupole moment, the binary interactions between the lattice ions and this quadrupole moment must be added to the dispersion and induced dipole interactions. For metallic solids, the principal interaction is between the gas atom and the sea of electrons in the solid. The ion cores contribute about 5% to the interactions. The quadratic terms account for harmonic oscillations, the cubic and higher order for the anharmonic ones. The elastic scattering theory for a perfect ionic crystal has been rather extensively treated, and intensity distributions in the scattered beams have been obtained. The simplest gas–solid scattering model is that of the rigid lattice with all atoms at their equilibrium sites. The lattice atoms are then dynamically inactive, and the gas atom moves in a fixed potential field.