Non-adiabatic current densities, transitions, and power absorbed by a molecule in a time-dependent electromagnetic field

Abstract

The energy of a molecule subject to a time-dependent perturbation separates completely into adiabatic and non-adiabatic terms, where the adiabatic term reflects the adjustment of the ground state to the perturbation, while the non-adiabatic term accounts for the transition energy [A. Mandal and K. L. C. Hunt, J. Chem. Phys. 137, 164109 (2012)]. For a molecule perturbed by a time-dependent electromagnetic field, in this work, we show that the expectation value of the power absorbed by the molecule is equal to the time rate of change of the non-adiabatic term in the energy. The non-adiabatic term is given by the transition probability to an excited state k, multiplied by the transition energy from the ground state to k, and then summed over the excited states. The expectation value of the power absorbed by the molecule is derived from the integral over space of the scalar product of the applied electric field and the non-adiabatic current density induced in the molecule by the field. No net power is absorbed due to the action of the applied electric field on the adiabatic current density. The work done on the molecule by the applied field is the time integral of the power absorbed. The result established here shows that work done on the molecule by the applied field changes the populations of the molecular states.

Periodic Energy Transport and Entropy Production in Quantum Electronics

“…The evaluation of the currents implies the evaluation of the exact Dyson equation (37) following the methods of [66,67]. A similar situation was analyzed in [91], where it was found that the rate of change for the nonadiabatic energy agrees with the work done on a molecule subjected to a time-dependent applied field. The work in [92] discusses heat transfer across a triple dot structure with the nonadiabatic driving applied to an edge dot.…”

Non-linear non-local molecular electrodynamics with nano-optical fields

“…The non-local response functions allow us to exactly calculate heterodyne detected optical signals in the presence of strong fields and non-uniform nano optical fields 12,38 . The formalism can be used to study non-adiabatic molecular current density dynamics 39 . Furthermore, it can be extended to cavity quantum electrodynamics (QED), or be used in understanding field angular momentum 40 .…”

Non-local real-space analysis of chiral optical signals

“…This reflects the fact that, in quantum mechanics, the interaction between charges and electromagnetic fields can be written in terms of the scalar-vector potential ( A 0 ( r ), A ( r )), which changes under gauge transformation, whereas all observables must be gauge invariant. 10 This makes the problem of nonlocal optical response rather involved.…”