Self-Consistent GW via Conservation of Spectral Moments

Résumé fourni par la source

High Resolution Image Download MS PowerPoint Slide We expand on a recently introduced alternate framework for GW simulation of charged excitations [ Scott, C. J. C. J. Chem. Phys. 2023, 158, 124102 ], based around the conservation of directly computed spectral moments of the GW self-energy. Featuring a number of desirable formal properties over other implementations, we also detail efficiency improvements and a parallelism strategy, resulting in an implementation with a demonstrably similar scaling to an established Hartree–Fock code, with only an order of magnitude increase in cost. We also detail the applicability of a range of self-consistent GW variants within this framework, including a scheme for full self-consistency of all dynamical variables, while avoiding the Matsubara axis or analytic continuation, allowing formal convergence at zero temperature. By investigating a range of self-consistency protocols over the GW 100 molecular test set, we find a little-explored self-consistent variant based around a simpler coupled chemical potential and Fock matrix optimization to be the most accurate self-consistent GW approach. Additionally, we validate recently observed evidence that Tamm–Dancoff-based screening approximations within GW lead to higher accuracy than traditional random phase approximation screening over these molecular test cases. Finally, we consider the Chlorophyll A molecule, finding agreement with experiment within the experimental uncertainty, and a description of the full-frequency spectrum of charged excitations.

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