Restricted and unrestricted non-Hermitian Hartree-Fock: Theory, practical considerations, and applications to metastable molecular anions

摘要

This work describes the implementation and applications of non-Hermitian self-consistent field (NH-SCF) theory with complex basis functions for the ab initio computation of positions and widths of shape resonances in molecules. We utilize both the restricted open-shell and the previously unexplored spin-unrestricted variants to compute Siegert energies of several anionic shape resonances in small diatomic and polyatomic molecules including carbon tetrafluoride which has been the subject of several recent experimental studies. The computation of general molecular properties from a non-Hermitian wavefunction is discussed, and a density-based analysis is applied to the B-2(1) shape resonance in formaldehyde. Spin-unrestricted NH-SCF is used to compute a complex potential energy surface for the carbon monoxide anion which correctly describes dissociation. (C) 2015 AIP Publishing LLC.