Atomistic Modeling of Irradiation-Induced Defects in Quantum-Confined Semiconductors

Irradiation can profoundly alter the optical and electronic performance of quantum dots (QDs), yet the atomic-scale mechanisms driving these effects remain elusive. Defects such as vacancies, interstitials, and antisites determine whether a QD retains luminescence, undergoes bandgap shifts, or experiences permanent damage. We develop an atomistically grounded framework that combines density functional theory (DFT) with ab initio molecular dynamics (AIMD) to model defect creation, migration, and annealing under irradiation. DFT captures defect energetics, charge transition levels, and local electronic structure, while AIMD reveals the time evolution of displaced atoms and transient defect populations. Mercury chalcogenide quantum dots (QDs) combine strong quantum confinement with narrow, tunable bandgaps that make them ideal for infrared optoelectronics, yet their response to irradiation remains poorly understood. Starting from atomically resolved zinc-blende models of HgTe and HgSe QDs, we explore how structural motifs, surface terminations, and local distortions influence defect energetics and electronic localization. Linking atomistic dynamics to observables such as photoluminescence quenching and spectral shifts provides new insight into radiation-induced processes and guides the design of stable, radiation-tolerant infrared nanomaterials.