Complex Absorbing Potential Green's Function Methods for Resonances
arXiv:2507.03496 · doi:10.1021/acs.jctc.5c01164
Abstract
The complex absorbing potential (CAP) formalism has been successfully employed in various wavefunction-based methods to study electronic resonance states. In contrast, Green's function-based methods are widely used to compute ionization potentials and electron affinities but have seen limited application to resonances. We integrate the CAP formalism within the approximation, enabling the description of electronic resonances in a Green's function framework. This approach entails a fully complex treatment of orbitals and quasiparticle energies in a non-Hermitian setting. We validate our CAP- implementation by applying it to the prototypical shape resonances of \ce{N2^-}, \ce{CO^-}, \ce{CO_2^-}, \ce{C2H2-}, \ce{C2H4-}, and \ce{CH2O-}. It offers a fast and practical route to approximate both the lifetimes and positions of resonance states, achieving an accuracy comparable to that of state-of-the-art wavefunction-based methods.
18 pages, 7 figures