Ab Initio Theory of Optical Activity in $α$-Quartz in the $GW$-Bethe-Salpeter-Equation Framework

Author(s): Xiaoming Wang and Yanfa Yan We present an ab initio many-body theory of optical activity in solids within the $GW$ approximation plus Bethe-Salpeter equation framework. Dielectric spatial dispersion is formulated in two complementary forms: exciton envelope modulation and sum-over-exciton-states expansion. Our application to $… [Phys. Rev. Lett. 136, 186901] Published Wed May 06, 2026