Nonadiabatic Nuclear-Electron Dynamics: A Quantum Computing Approach

Coupled quantum electron-nuclear dynamics is oftenassociatedwith the Born-Huang expansion of the molecular wave functionand the appearance of nonadiabatic effects as a perturbation. On theother hand, native multicomponent representations of electrons andnuclei also exist, which do not rely on any a priori approximation.However, their implementation is hampered by prohibitive scaling.Consequently, quantum computers offer a unique opportunity for extendingtheir use to larger systems. Here, we propose a quantum algorithmfor simulating the time-evolution of molecular systems and apply itto proton transfer dynamics in malonaldehyde, described as a rigidscaffold. The proposed quantum algorithm can be easily generalizedto include the explicit dynamics of the classically described molecularscaffold. We show how entanglement between electronic and nucleardegrees of freedom can persist over long times if electrons do notfollow the nuclear displacement adiabatically. The proposed quantumalgorithm may become a valid candidate for the study of such phenomenawhen sufficiently powerful quantum computers become available