# The origin of the core-level binding energy shifts in nanoclusters

## TL;DR

This paper uses ab initio calculations to analyze how core-level binding energies in gold nanoclusters vary with size and structure, revealing complex dependencies on atomic and electronic factors.

## Contribution

It provides a detailed understanding of the origins of core-level shifts in gold nanoclusters, highlighting three main contributing factors and their dependence on cluster properties.

## Key findings

- Core-level shifts depend non-monotonically on cluster size.
- Three main contributions to the shifts are identified: interatomic distances, coordination, and quantum confinement.
- Shifts are explained by changes in the on-site electrostatic potential.

## Abstract

We investigate the shifts of the core-level binding energies in small gold nanoclusters by using {\it ab initio} density functional theory calculations. The shift of the 4$f$ states is calculated for magic number nanoclusters in a wide range of sizes and morphologies. We find a non-monotonous behavior of the core-level shift in nanoclusters depending on the size. We demonstrate that there are three main contributions to the Au 4$f$ shifts, which depend sensitively on the interatomic distances, coordination and quantum confinement. They are identified and explained by the change of the on-site electrostatic potential.