Quantum-mechanical simulation of laser-induced alignment of asymmetric-top molecules at high temperatures

Quantum-mechanical simulation of laser-induced alignment of asymmetric-top molecules at high temperatures has been a challenge due to the high computational cost required to model a large number of initial states of the molecular ensemble. Here, we report a method to reduce the computational time and memory requirements by using the symmetries of coefficients in the rotational wave packet. For the case of nonadiabatic alignment of asymmetric-top molecules with a linearly polarized laser pulse, we have theoretically derived the symmetries in the coefficients of the rotational wave packet produced by the induced-dipole interaction. The symmetries allow us to simulate rotational dynamics at higher rotational temperatures than previously possible by reducing both the memory requirements and the computation time by a factor of 8. We demonstrate simulated results of the rotational dynamics of 4-fluorobenzotrifluoride at multiple temperatures up to 300 K.