2018/11/30 by Hugh G. A. Burton, Alex J. W. Thom, Pierre-François Loos
Chemistry · Physics and Astronomy · #Adiabatic process #Advanced Chemical Physics Studies #Advanced Physical and Chemical Molecular Interactions #Energy (signal processing) #Excited state #Function (biology) #Path (computing) #Quantum #Quantum Mechanics and Non-Hermitian Physics #Wave function #physics.chem-ph
paper · pdf · doi:10.1063/1.5085121
published as J. Chem. Phys. 150, 041103 (2019) · 5 pages, 3 figures
openalex created_date 2019/01/11 · arxiv created 2019/01/14 · openalex publication_date 2019/01/25 · arxiv updated 2020/06/05 · openalex updated_date 2026/08/05
Processes related to electronically excited states are central in many areas of science; however, accurately determining excited-state energies remains a major challenge in theoretical chemistry. Recently, higher energy stationary states of non-linear methods have themselves been proposed as approximations to excited states, although the general understanding of the nature of these solutions remains surprisingly limited. In this letter, we present an entirely novel approach for exploring and obtaining excited stationary states by exploiting the properties of non-Hermitian Hamiltonians. Our key idea centres on performing analytic continuations of conventional quantum chemistry methods. Considering Hartree-Fock theory as an example, we analytically continue the electron-electron interaction to expose a hidden connectivity of multiple solutions across the complex plane, revealing a close resemblance between Coulson-Fischer points and non-Hermitian degeneracies. Finally, we demonstrate how a ground-state wave function can be morphed naturally into an excited-state wave function by constructing a well-defined complex adiabatic connection.