Density functional theory calculations and thermodynamic analysis of the forsterite $Mg_{2}SiO_{4}$(010) surface

TL;DR

This study uses density functional theory to analyze the stability of different forsterite (Mg2SiO4) (010) surface terminations under various chemical conditions, providing a phase diagram for surface stability relevant to planetary science.

Contribution

It presents a thermodynamic approach combined with DFT calculations to determine the most stable surface terminations of forsterite under different environments.

Findings

SiO-II, M2, O-II terminations are most stable across conditions.

Stability order persists at elevated temperatures.

Surface phase diagram aids understanding of planetary surface processes.

Abstract

The stability of possible termination structures for the (010) surface of forsterite, $ Mg_2SiO_4 $, is studied using a density functional theory (DFT) based thermodynamic approach. The DFT calculations are used to estimate the surface Gibbs free energy of various surface structures and compare their stability as a function of the chemical environment. Among 9 possible terminations, the SiO-II, M2, O-II terminations are found to be most stable as conditions range from Mg-poor to Mg-rich. This relative stability order remains the same at an elevated temperature. The surface phase diagram obtained provides ground for further theoretical studies of chemical processes on forsterite surfaces in terrestrial planets.