  The coupled quantum dynamics of electrons and protons is ubiquitous in many
dynamical processes involving light-matter interaction, such as solar energy
conversion in chemical systems and photosynthesis. A first-principles
description of such nuclear-electronic quantum dynamics requires not only the
time-dependent treatment of nonequilibrium electron dynamics but also that of
quantum protons. Quantum mechanical correlation between electrons and protons
adds further complexity to such coupled dynamics. Here we extend real-time
nuclear-electronic orbital time-dependent density functional theory
(RT-NEO-TDDFT) to periodic systems and perform first-principles simulations of
coupled quantum dynamics of electrons and protons in complex heterogeneous
systems. The process studied is electronically excited state intramolecular
proton transfer of o-hydroxybenzaldehyde in water and at a silicon (111)
semiconductor-molecule interface. These simulations illustrate how environments
such as hydrogen-bonding water molecules and an extended material surface
impact the dynamical process on the atomistic level. Depending on how the
molecule is chemisorbed on the surface, excited state electron transfer from
the molecule to the semiconductor surface can inhibit ultrafast proton transfer
within the molecule. This work elucidates how heterogeneous environments
influence the balance between the quantum mechanical proton transfer and
excited electron dynamics. The periodic RT-NEO-TDDFT approach is applicable to
a wide range of other photoinduced heterogeneous processes.
