Dynamically Corrected Bethe-Salpeter Equation Solver for Self-consistent Reference on the Matsubara Frequency Axis
arXiv:2604.22187
Abstract
We present a Bethe-Salpeter equation (BSE) solver based on a self-consistent reference evaluated on the Matsubara frequency axis, referred to as BSE@sc. The self-consistent starting point provides a robust quasiparticle description and reduces sensitivity to the initial mean-field reference compared to one-shot -based approaches. We further introduce a dynamical correction to the static Casida formulation via a plasmon-pole model. This scheme incorporates simple dynamical screening effects while retaining the efficiency of an effective eigenvalue problem. The resulting dynamically corrected BSE@sc yields excitation energies in close agreement with high-level wavefunction-based benchmarks for both singlet and triplet excitations of small molecules. Overall, the accuracy of the dynamic BSE@sc approach arises from the combination of a well-converged single-particle reference and the inclusion of frequency-dependent screening effects.
19 pages, 6 figures