Ab initio nonadiabatic molecular dynamics investigations on the excited carriers in condensed matter systems

Abstract

The ultrafast dynamics of photoexcited charge carriers in condensed matter systems play an important role in optoelectronics and solar energy conversion. Yet it is challenging to understand such multidimensional dynamics at the atomic scale. Combining the real‐time time‐dependent density functional theory with fewest‐switches surface hopping scheme, we develop time‐dependent ab initio nonadiabatic molecular dynamics (NAMD) code Hefei‐NAMD to simulate the excited carrier dynamics in condensed matter systems. Using this method, we have investigated the interfacial charge transfer dynamics, the electron–hole recombination dynamics, and the excited spin‐polarized hole dynamics in different condensed matter systems. The time‐dependent dynamics of excited carriers are studied in energy, real and momentum spaces. In addition, the coupling of the excited carriers with phonons, defects and molecular adsorptions are investigated. The state‐of‐art NAMD studies provide unique insights to understand the ultrafast dynamics of the excited carriers in different condensed matter systems at the atomic scale. This article is categorized under: Structure and Mechanism > Computational Materials Science Molecular and Statistical Mechanics > Molecular Dynamics and Monte‐Carlo Methods Electronic Structure Theory > Ab Initio Electronic Structure Methods Software > Simulation Methods

Low-frequency lattice phonons in halide perovskites explain high defect tolerance toward electron-hole recombination

“…As have been discussed in the previous studies (33,34), the e-h recombination rate is strongly dependent on the NAC between the donor and acceptor states. The NAC matrix element d jk can be expressed as…”

“…Here, H is the Kohn-Sham (KS) Hamiltonian; φ j , φ k , ϵ j , and ϵ k are the wave functions and eigenvalues for donor and acceptor states j and k, respectively; and Ṙ is the nuclear velocity (34). The first equality in Eq.…”

Soft Lattice and Defect Covalency Rationalize Tolerance of β‐CsPbI3 Perovskite Solar Cells to Native Defects

“…The e‐h recombination times obtained in NAMD simulations are strongly dependent on the band gap, pure‐dephasing time, and NAC between the donor and acceptor states –. Generally, larger band gap, shorter pure‐dephasing time and weaker NAC lead to slower e‐h recombination.…”

Surface hopping methods for nonadiabatic dynamics in extended systems

“…Another issue that limits the application of surface hopping is the large number of trajectories required to obtain the converged results. CPA can significantly reduce the number of trajectories as the nuclear dynamics is assumed to be independent of the electron evolution . Recently, Cerrillo and Cao proposed the transfer tensor method, which could efficiently propagate the state of the system to arbitrarily long‐time scales using the short‐time mixed quantum‐classical Liouville dynamical maps as input .…”