Yosuke Kanai (UNC Chapel Hill)
All-electron Bethe-Salpeter equation approach for core electron excitation

I will discuss an accurate first-principles computational approach to calculate absolute K-edge core electron excitation energies as measured by X-ray absorption spectroscopy. Our approach employs an all-electron Bethe-Salpeter equation (BSE) formalism based on GW approximation to Hedin's equations (BSE@GW). The many-body perturbation theory formalism has become an increasingly popular method for first-principles computation of neutral valence excitation energies of condensed matter and molecular systems in the last few decades. However, its application to core electron excitation has been largely unexplored. I will discuss the influence of different approximations in the BSE@GW calculation and show its great accuracy with a benchmark set of small organic molecules, previously used for the equation-of- motion coupled cluster method.