RUI: Exciton-Phonon Interactions in Solids based on Time-Dependent Density Functional Perturbation Theory

The main objective of the project is to develop an accurate, efficient and robust ab initio approach capturing exciton-phonon interactions in solids to address cutting-edge scientific problems . The method is based on time-dependent density functional perturbation theory (TDDFPT) and will be implemented in major open source software, Quantum ESPRESSO, as a plug-and-compute module. The proposed TDDFT method can compute the exciton band structure (i.e., exciton energies as a function of momentum Q) in solids, charge density and ionic forces associated with the exciton state, non-adiabatic couplings between exciton states, exciton-phonon coupling matrix, and exciton dynamical processes rigorously based on planewaves and pseudopotentials. Three levels of parallelization over exciton states, k-points, and electronic bands will be exploited, rendering the codes amenable to massively parallel platforms. The developed codes will be freely available to the computational materials community. Finally, we propose to use the developed method to study the phonon-assisted interfacial charge transfer and Dexter-type interfacial energy transfer in 2D van der Waals (vdW) heterostructures, unraveling the momentum transfer between exciton and phonons as well as intra/interlayer exciton-phonon interactions during the interfacial exciton dynamics.