  We demonstrate (both analytically and numerically) total angular momentum
conservation for a molecular system subject to circularly polarized light (CPL)
field moving along a single Born-Oppenheimer surface, where all of the angular
momentum transfer is embodied in a Berry force. Moreover, we demonstrate that
the model Hamiltonian proposed in [J. Chem. Phys. 150, 124101 (2019)] in fact
corresponds physically to a homonuclear diatomic in a CPL field. Our results
not only reveal an interesting microscopic mechanism for angular momentum
transfer between a molecule and a radiation field, but they also provide new
insight into the nature of novel semiclassical non-adiabatic dynamics methods
that conserve the total angular momentum (including, e.g., phase-space
surface-hopping methods).
