Temperature dependence of (111) and (110) ceria surface energy

TL;DR

This study investigates how the surface energies of (111) and (110) ceria surfaces change with temperature using advanced computational methods, highlighting the importance of anharmonic effects for accurate predictions.

Contribution

The paper introduces a novel combination of thermodynamic integration with machine learning potentials to accurately model temperature-dependent surface energies of ceria surfaces.

Findings

Surface energies decrease with temperature for both surfaces.

Anharmonic effects are crucial for accurate energy predictions.

Method improves understanding of high-temperature ceria surface properties.

Abstract

High temperature properties of ceria surfaces are important for many applications. Here we report the temperature dependences of surface energy for the (111) and (110) CeO2 obtained in the framework of the extended two-stage upsampled thermodynamic integration using Langevin dynamics (TU-TILD). The method was used together with machinelearning potentials called moment tensor potentials (MTPs), which were fitted to the results of the ab initio MD calculations for (111) and (110) CeO2 at different temperatures. The parameters of MTPs training and fitting were tested and the optimal algorithm for the ceria systems was proposed. We found that the temperature increases from 0 K to 2100 K led to the decrease of the Helmholtz free energy of (111) CeO2 from 0.78 J/m2 to 0.64 J/m2. The energy of (110) CeO2 dropped from 1.19 J/m2 at 0 K to 0.92 J/m2 at 1800 K. We show that it is important to take anharmonicity into account as simple consideration of volume expansion gives wrong temperature dependences of the surface energies.