Ab-initio density functional studies of stepped TaC surfaces

TL;DR

This study uses ab-initio density functional theory to analyze the energetics and atomic structure of stepped TaC surfaces, revealing favored step heights and predicting observable surface rumpling.

Contribution

It provides new insights into the atomic displacements and charge localization at TaC step edges, aligning with experimental findings on step stability.

Findings

Double and triple-height steps are energetically favored.

Predicted rumpled structure of step-edges with significant Ta atom displacements.

Agreement with recent experimental observations on step stability.

Abstract

We report on density functional total energy calculations of the step formation and interaction energies for vicinal TaC(001) surfaces. Our calculations show that double and triple-height steps are favored over single-height steps for a given vicinal orientation, which is in agreement with recent experimental observations. We provide a description of steps in terms of atomic displacements and charge localization and predict an experimentally observable rumpled structure of the step-edges, where the Ta atoms undergo larger displacements compared to the C atoms.