Intermolecular potential energy extrapolation method for weakly bound systems: Ar₂, Ar–H₂ and Ar–HF dimers

Abstract

Two methods are presented and compared for modifying the intermolecular potential energy extrapolation routine SIMPER, to overcome the problems occurring at small intermolecular separation associated with the use of a Coulomb approximation. The first modification uses a charge density overlap pseudopotential added to the effective Hamiltonian of each interacting fragment. The second treats the problem perturbatively, truncating the polarization expansion series at third order. The methods are used to produce potential energy curves for Ar₂ dimer and several one-dimensional cuts through the Ar–H₂ and Ar–HF potential energy surfaces. Both approaches are competitive with supermolecule dimer calculations at high levels of theory, and significantly reduce the computational cost.

Notes

†Present address: Department of Chemistry, University of Sussex, Falmer, Brighton BN1 9QJ, UK.

Additional information

Notes on contributors

Richard J. Wheatley

†Present address: Department of Chemistry, University of Sussex, Falmer, Brighton BN1 9QJ, UK.