# An information-theoretic approach to nonadiabatic quantum molecular dynamics

**Project level:** PhD

This project involves using minimal physical Hamiltonian models to study the flow of energy and information associated with the dynamical breakdown of the Born-Oppenheimer approximation (BOA). The BOA is the fundamental approximation on which quantum chemistry is based; its physical content is the assertion that the electrons in a molecule react infinitely fast relative to the dynamics of the nuclei. Breakdown of the BOA is essential to electronic decay following excitation, and is an intrinsic feature of photochemical reaction mechanisms. Breakdown of the BOA is dominated by so-called "conical intersections" i.e. points of degeneracy between electronic potential energy surfaces. One of the characteristics of dynamics at these points is that the electronic and nuclear degress of freedom cannot be separated, so that entropy production (or elimination) in the separate nuclear and electronic subsystems is possible.

The student will employ the information-theoretic approach to molecular dynamics to study the entropy production in the electonic and nuclear manifolds during dynamics simulated using parametric models of conical intersections and close avoided crossings.

This research topic is at the forefront of modern chemical physics, and also overlaps with current problems in quantum information theory and algebraic approaches to quantum dynamics. The information-theoretic approach to molecular quantum dynamics (described in e.g. Alhassid, Y., & Levine, R. (1977). ENTROPY AND CHEMICAL CHANGE .3. MAXIMAL ENTROPY (SUBJECT TO CONSTRAINTS) PROCEDURE AS A DYNAMICAL THEORY. The Journal of Chemical Physics, 67(10), 4321–4339. and subsequent papers).