Multiorbital impact on strong-field ionization of HCl molecules

Abstract

We have put forward the time-dependent Hartree-Fock approach to investigate ionization dynamics of HCl molecules subjected to strong few-cycle laser pulses, which is based on the finite-element discrete-variable representation in prolate spheroidal coordinates and the Crank-Nicolson method. It is demonstrated that the electron is favored to be freed by the peak electric field pointing towards the H atom for the HCl molecule possessing the bonding length $R=2.5$ a.u., while the ionization prefers to occur for the maximum electric field pointing from the H nucleus to Cl nucleus with increasing internuclear separations. Analysis indicates that the ionization yield of $5\ensuremath{\sigma}$ electrons becomes significant with respect to that of $2\ensuremath{\pi}$ electrons with stretching bonding lengths, and the relative contributions of the ionization from $5\ensuremath{\sigma}$ and $2\ensuremath{\pi}$ electrons change as a function of internuclear separations, which gives rise to the above distinct oriented ionization of HCl molecules.