Laser-induced dynamics of molecules with strong nuclear quadrupole coupling

TL;DR

This paper introduces a variational method combining TROVE and RichMol to accurately simulate laser-induced rovibrational dynamics in molecules with nuclear quadrupole hyperfine effects, revealing long-term dephasing impacts.

Contribution

It develops a novel variational approach integrating hyperfine effects into rovibrational dynamics simulations, enhancing accuracy for molecules with nuclear quadrupole coupling.

Findings

Nuclear quadrupole interactions have negligible effects at early times post-pulse.

Long-term dynamics are significantly affected by hyperfine-induced dephasing.

The method accurately predicts the influence of hyperfine effects on molecular alignment.

Abstract

We present a general variational approach for computing the laser-induced rovibrational dynamics of molecules taking into account the hyperfine effects of the nuclear quadrupole coupling. The method combines the general variational approach TROVE, which provides accurate rovibrational hyperfine energies and wave functions for arbitrary molecules, with the variational method RichMol, designed for generalized simulations of the rovibrational dynamics in the presence of external electric fields. We investigate the effect of the nuclear quadrupole coupling on the short-pulse laser alignment of a prototypical molecule CFClBrI, which contains nuclei with large quadrupole constants. The influence of the nuclear quadrupole interactions on the post-pulse molecular dynamics is negligible at early times, first several revivals, however at longer timescales the effect is entirely detrimental and strongly depends on the laser intensity. This effect can be explained by dephasing in the laser-excited rotational wavepacket due to irregular spacings between the hyperfine-split nuclear spin states across different rotational hyperfine bands.