Quantum mechanical embedding theory based on a unique embedding potential.

Abstract

This study addresses the nonuniqueness problem inherent in conventional quantum mechanical embedding approaches by requiring both the environment and the embedded region to share a single common interaction potential. An optimized effective potential formalism was derived to solve for this shared potential efficiently, avoiding reliance on approximate kinetic energy density functionals. The embedded correlated wavefunction method was validated by computing van der Waals binding energy curves for a hydrogen molecule interacting with a hydrogen chain. Application to CO adsorption on the Cu(111) metal surface yielded correct site ordering (top site as most stable) and accurate binding energies. Significant changes in the p-character of CO 4σ and 5σ orbitals upon adsorption were observed, consistent with x-ray emission spectra. The framework was further extended to spin-polarized quantum systems, and its relationship to partition density functional theory was discussed.

Mechanism

Nonuniqueness is eliminated by enforcing a shared embedding potential between environment and embedded regions; an optimized effective potential method enables correlated wavefunction treatment without approximate kinetic energy functionals.