Convergence Tests and Surface Energy Calculation of Au (111) using Density Functional Theory

Abstract

Accurate numerical convergence is crucial for prediction of surface property using density functional theory (DFT). In this work, we use Quantum ESPRESSO with PBE-PAW pseudopotentials to conduct a systematic convergence analysis of the kinetic-energy cutoff, k-point density, and lattice parameter for bulk Au. Bulk optimization was performed by varying the lattice constant from 3.94 Å to 4.22 Å, yielding an optimized value of 4.06 Å in agreement with experimental findings. The surface energy of the unreconstructed Au (111) surface was determined to be 1.20   using converged parameters, which is consistent with reported theoretical and experimental results. This study provides reliable, benchmark computational parameters for further investigations of adsorption, catalysis, and electrochemical phenomena on the gold Au (111) surface, specifically the unreconstructed phase