An accurate and efficient semiclassical method for high-order harmonic generation from polyatomic molecules

We demonstrate applications of our recently developed semiclassical strong-field Herman–Kluk (SFHK) propagator method to calculations of high-order harmonic generation (HHG) in polyatomic molecules driven by ultrafast intense laser fields. First, we benchmark our results against the exact numerical solutions of the time-dependent Schrodinger equation. Second, to compare with experimental data, we carry out the averaging over molecular orientations. This typically involves three-dimensional (3D) integrations over Euler angles for polyatomic molecules. Here we demonstrate a powerful advantage of the SFHK method, as its intrinsic Monte Carlo sampling enables efficient evaluations of combined multidimensional integrals, together with the integrals over the initial momentum distributions of electron wave-packet right after the tunnel exit.

This work was supported by the U.S. Department of Energy (DOE), Office of Science, Basic Energy Sciences (BES) under Award Number DE-SC0023192.