Structure, Dynamics and Themodynamics of a metal chiral surface: Cu(532)

TL;DR

This study investigates the structure, vibrational dynamics, and thermodynamics of the chiral Cu(532) surface using a local harmonic approximation, revealing complex relaxation patterns and significant vibrational entropy contributions.

Contribution

It provides a detailed analysis of the atomic relaxation, vibrational density of states, and thermodynamic properties of Cu(532), highlighting the impact of low coordination on surface behavior.

Findings

Atomic relaxation involves strong bond contractions and expansions near kink and step sites.

Vibrational density of states deviates from bulk behavior down to the 10th layer.

Vibrational entropy contributes approximately 90 meV to the free energy at 300K.

Abstract

The structure, vibrational dynamics and thermodynamics of a chiral surface, Cu(532), has been calculated using a local approach and the harmonic approximation, with interatomic potentials based on the embedded atom method. The relaxation of atomic positions to the optimum configuration results in a complex relaxation pattern with strong contractions in the bond length of atoms near the kink and the step site and an equivalently large expansion near the least under-coordinated surface atoms. The low coordination of the atoms on the surface affects substantially the vibrational dynamics and thermodynamics of this system. The local vibrational density of states show a deviation from the bulk behavior that persist down to the 10th layer resulting in a substantial contribution of the vibrational entropy to the excess free energy amounting to about 90 meV per unit cell at 300K.