First-principles study of ultrafast bandgap dynamics in laser-excited $$\alpha$$-quartz

Femtosecond-laser-induced evolution of -quartz bandgap was calculated using rst principles. First,Time-Dependent Density Functional Theory (TDDFT) was used to describe excited electron dynamicsduring the laser pulse irradiation. Then the temperature of excited electrons was estimated usingFinite-Temperature DFT. Finally, the GW approximation was applied to calculate the electronicstructure modication driven by hot electrons. As a result, an ultrafast decrease of the bandgap isobserved during a 15-fs laser pulse with a drop of 35 % at laser intensities near the damage threshold