First-Principles Study of the Temperature Dependence of Structural, Electronic, and Hyperfine Properties of the Cu(100) Surface

TL;DR

This study uses first-principles calculations to analyze how temperature affects the structural, electronic, and hyperfine properties of the Cu(100) surface, focusing on electric-field gradient behavior.

Contribution

It provides a comprehensive ab initio analysis of temperature-dependent surface reconstruction and hyperfine properties, linking bulk and surface effects.

Findings

EFG exhibits linear temperature dependence at the surface.

Surface reconstruction influences the anisotropic relaxation and EFG.

Bulk temperature-dependent lattice parameters are crucial for accurate surface property modeling.

Abstract

In this work, we investigate the temperature-dependent behavior of the pure (undoped) Cu(100) surface using first-principles calculations within the Density Functional Theory framework. One of the main objectives is to determine whether the linear dependence of the predicted electric-field gradient (EFG) tensor on the outermost Cu atom on the Cu(100) surface arises from the same generation of the surface or from the reconstruction of the surface. To this end, we perform here a comprehensive $\it{ab}$ $\it{initio}$ study of the Cu(100) surface reconstruction and its associated structural, electronic, and hyperfine properties as a function of temperature, not only at the outermost atomic layer (i.e., the topmost Cu atom) but also as a function of atomic depth relative to the reconstructed surface. To study the temperature dependence of the EFG, we use experimentally determined temperature-dependent lattice parameters for bulk copper in our calculations. The anisotropic relaxation that arises when bulk symmetry is broken helps unravel the potential sources of EFG temperature dependence at the surface. Studying the electron density of conduction electrons $\rho$($\bf{r}$) at the atomic scale near the Cu nucleus and the atom-resolved partial density of states at the topmost Cu atom allows us to correlate the surface effect on the EFG with the bulk value. Finally, we correlate the temperature dependence of the EFG on the undoped Cu(100) surface with the linear behavior of the ''ionic'' contribution to the EFG.