Non-adiabatic Exciton Dynamics in van der Waals Heterostructures

In this Perspective, we introduce a first-principles method that combines time-dependent density functional theory with non-adiabatic molecular dynamics (NAMD) to explore exciton dynamics in two-dimensional (2D) van der Waals (vdW) heterostructures. The theoretical foundation and computational efficiency of the method are discussed and compared with those of related methods (e.g., GW-BSE). Using three 2D v d W heterostructures as examples, we demonstrate that the proposed method can provide a reliable description of many-body electron-hole interactions crucial to exciton dynamics. With much lower computational costs t h a n the GW-BSE method, the proposed method represents a particularly promising theoretical tool to probe exciton dynamics in solids. Moreo v e r , we find that the NAMD simulations widely used in the literature cannot capture the excitonic effect in 2D materials and often yield incorrect results because they are formulated in a single-particle picture. The instances where the single-particle picture fails are pointed out and contrasted with the many-body simulation results.

Automated summary

This Perspective introduces a first-principles method that combines time-dependent density functional theory with non-adiabatic molecular dynamics to study exciton dynamics in two-dimensional van der Waals heterostructures. The method is shown to provide a reliable description of many-body electron-hole interactions crucial to exciton dynamics, and it is also compared with other related methods. Additionally, it highlights the limitations of commonly used NAMD simulations in capturing excitonic effects in 2D materials.