Density Functional Theory Calculations and Thermodynamic Analysis of the Forsterite Mg₂SiO₄(010) Surface

Abstract

The stability of possible termination structures for the (010) surface of forsterite, M g2SiO4, 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 functions 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 elevated temperature. The surface phase diagram obtained provides ground for further theoretical studies of chemical processes on forsterite surfaces in terrestrial planets.

The stability and electronic and photocatalytic properties of the ZnWO4 (010) surface determined from first-principles and thermodynamic calculations

“…The entropy's contributions and the pressure-volume work to their respective Gibbs free energy can be safely ignored. [40][41][42] We will also ignore the vibration in our DFT calculation because its contributions can easily be disregarded. 40,41 Therefore, the Gibbs free energies are considered as total energies of orthorhombic ZnWO 4 per formula, which can be obtained from our DFT calculation:…”

“…Here, DG(T,p) is the temperature-dependent variation of Gibbs free energy of oxygen when at standard pressure p 0 , available from thermodynamic Tables. [39][40][41] The last term is…”

Site preference of Fe atoms in the olivine $(Fe_xMg_{2-x})SiO_4$ and its surface

“…9 We construct a series iron contained olivine surface slabs based on two types (Figure . 5) most possible exposed surface terminations one type with M 2 site exposed and another type with M 1 site exposed based on our previous studies. 22 The M 2 exposed type of surfaces are relative more flat than the M 1 exposed ones, no matter the iron atoms are on the top or not.…”

The surface reconstruction induced enhancement of the oxygen evolution reaction on α-SnWO4 (010) based on a density functional theory study

“…The surface Gibbs free energy can determine the stability of a surface as a function of environmental conditions. 28 The surface Gibbs free energy Ω (SnWO 4 ) could be represented via the formula, 28–31 Here, is the total Gibbs free energy of the α-SnWO 4 (010) slab. The μ i (i = Sn, W, O) is the chemical potential of Sn, W, and O.…”