Effective Residual Interaction Kernel Approach for Optical Spectra
Phys. Rev. Lett. 137, 126901 – Published 14 September, 2026
DOI: https://doi.org/10.1103/nk3g-crbw
Abstract
Excitonic effects dominate absorption and loss spectra in many materials. However, they are hard to access computationally, because of the cost of first-principles calculations and because of the scarce reliability of simple approximations. We overcome both limitations by combining a part of the electron-hole Bethe-Salpeter equation with an effective scalar interaction. The partitioning is motivated by the general form of the electron-hole interaction and it can be applied to all materials. First-principles calculations for prototypical semiconductors and insulators demonstrate a speedup of 1 to 2 orders of magnitude for results close to those where the full interaction matrix is used. The method is systematic and can be converged to the benchmark.