Electronic Structure of Water from Koopmans-Compliant Functionals

Obtaining a precise theoretical description of the spectral properties liquid water poses challenges for both molecular dynamics (MD) and electronic structure methods. The lower computational cost Koopmans-compliant functionals with respect to Green's function methods allows simulations many MD trajectories, close state-of-art quasi-particle self-consistent GW plus vertex corrections method (QSGW+f$_{xc}$). Thus, we explore when different approaches are used, ranging from classical first-principles MD, including nuclear quantum effects. We have observed that lead up 1 eV change in average band gap, thus, focused on gap dependence geometrical system explain such spread. evaluated changes due variations intramolecular O-H bond distance, HOH angle, as well intermolecular hydrogen O$\cdot\cdot\cdot$O OHO angles. dominant contribution comes length; distance plays secondary role, other do not significantly influence gap. Furthermore, analyze density states (DOS), where KIPZ functional shows good agreement DOS obtained employing corrections. length also influences DOS. When effects considered, broadening peaks driven by broader distribution lengths is observed, leading closer experimental photoemission spectra.