Electronic resonances: Challenge and opportunity
Seminar | September 26 | 4-5 p.m. | 120 Latimer Hall
Autoionizing (or electron-detaching) states are ubiquitous in physics, chemistry, biology, and technology. Such meta-stable states (called resonances) play a central role in processes as diverse as DNA radiolysis, plasmonic catalysis, and attosecond spectroscopy. Resonances belong to the continuum spectrum, which makes their theoretical description exceptionally difficult, because their wave functions are not L2-integrable and cannot be represented by expansions over gaussian basis sets. This theoretical challenge can be overcome by reformulating many-body methods in the non-Hermitian framework. When combined with robust electronic structure methods, such as the equation-of-motion coupled-cluster approach, these techniques enable first-principle description of electronic resonances. While a challenge to the methodology, resonances are also an opportunity to extend important quantum-chemistry concepts to a new domain of electronic structure. I will present the theory of the equation-of-motion coupled-cluster method augmented by complex absorbing potential. Salient features of this approach will be illustrated by examples, with an emphasis on the connections to experimental observables. I will also discuss the extension of Huckel theory, Dyson orbitals, and dipole-bound states to the domain of electronically unbound, metastable states.
 T.-C. Jagau, K.B. Bravaya, and A.I. Krylov, Extending quantum chemistry of bound states to electronic resonances, Ann. Rev. Phys. Chem. 68, 525 553 (2017).
Light refreshments will be served at 3:50 at The Coffee Lab