Tuning the Electronic Structure and Stability of Au 38 (SR) 24 Nanoclusters via Site-Selective Palladium Doping

Abstract

This study presents a systematic computational investigation into the structural, energetic, electronic, and optical properties of palladium-doped isomers of the Au 38 (SR) 24 nanocluster, with a specific focus on the [Au 38 (SR) 24 ] T structure, a isomer of bi-icosahedral Au 38 (SR) 24 (denoted as [Au 38 (SR) 24 ] Q ). Using density functional theory (DFT) and time-dependent DFT (TDDFT) calculations, we demonstrate that single-atom Pd doping at the central site of the Au 13 icosahedron in the T-isomer to form [Au 37 Pd 1 (SR) 24 ] T is energetically feasible and yields a stable cluster. However, a critical isomer-dependent stability emerges for double doping, as the incorporation of a second Pd atom to form [Au 36 Pd 2 (SR) 24 ] T is significantly less favorable than its Qisomer analogue. Electronically, Pd doping effectively narrows the HOMO-LUMO gap in both systems by modulating the Kohn-Sham frontier orbital energy levels, primarily through the hybridization of Pd-4d states with the original Au-sp and Au-d orbitals.This electronic restructuring induces a distinct red-shift in the optical absorption spectra.Analysis of the density of states and the spatial distributions of the frontier orbitals confirms significant Pd contributions, revealing a notable difference in orbital composition between the T and Q isomer series. These findings not only validate the viability of Pd doping in the previously unexplored [Au 38 (SR) 24 ] T isomer but also provide fundamental principles for the rational design of isomer-specific doped nanoclusters with tailored optical properties.