TY - JOUR

T1 - Efficient ab initio schemes for finding thermodynamically stable and metastable atomic structures

T2 - Benchmark of cascade genetic algorithms

AU - Bhattacharya, Saswata

AU - Levchenko, Sergey V.

AU - Ghiringhelli, Luca M.

AU - Scheffler, Matthias

PY - 2014/12/8

Y1 - 2014/12/8

N2 - A first principles-based methodology for efficiently and accurately finding thermodynamically stable and metastable atomic structures is introduced and benchmarked. The approach is demonstrated for gas-phase metal-oxide clusters in thermodynamic equilibrium with a reactive (oxygen) atmosphere at finite pressure and temperature. It consists of two steps. First, the potential-energy surface is scanned by means of a global-optimization technique, i.e., a massive-parallel first-principles cascade genetic algorithm for which the choice of all parameters is validated against higher-level methods. In particular, we validate (a) the criteria for selection and combination of structures used for the assemblage of new candidate structures, and (b) the choice of the exchange-correlation functional. The selection criteria are validated against a fully unbiased method: replica-exchange molecular dynamics. Our choice of exchange-correlation functional, the van der Waals-corrected PBE0 hybrid functional, is justified by comparisons up to the highest level currently achievable within density-functional theory, i.e., the renormalized second-order perturbation theory. In the second step, the low-energy structures are analyzed by means of ab initio atomistic thermodynamics in order to determine compositions and structures that minimize the Gibbs free energy at given temperature and pressure of the reactive atmosphere.

AB - A first principles-based methodology for efficiently and accurately finding thermodynamically stable and metastable atomic structures is introduced and benchmarked. The approach is demonstrated for gas-phase metal-oxide clusters in thermodynamic equilibrium with a reactive (oxygen) atmosphere at finite pressure and temperature. It consists of two steps. First, the potential-energy surface is scanned by means of a global-optimization technique, i.e., a massive-parallel first-principles cascade genetic algorithm for which the choice of all parameters is validated against higher-level methods. In particular, we validate (a) the criteria for selection and combination of structures used for the assemblage of new candidate structures, and (b) the choice of the exchange-correlation functional. The selection criteria are validated against a fully unbiased method: replica-exchange molecular dynamics. Our choice of exchange-correlation functional, the van der Waals-corrected PBE0 hybrid functional, is justified by comparisons up to the highest level currently achievable within density-functional theory, i.e., the renormalized second-order perturbation theory. In the second step, the low-energy structures are analyzed by means of ab initio atomistic thermodynamics in order to determine compositions and structures that minimize the Gibbs free energy at given temperature and pressure of the reactive atmosphere.

KW - atomistic thermodynamics

KW - cascade genetic algorithm

KW - clusters

KW - density functional theory

KW - MgO

KW - reactive environment

UR - http://www.scopus.com/inward/record.url?scp=84927534128&partnerID=8YFLogxK

U2 - 10.1088/1367-2630/16/12/123016

DO - 10.1088/1367-2630/16/12/123016

M3 - Article

AN - SCOPUS:84927534128

VL - 16

JO - New Journal of Physics

JF - New Journal of Physics

SN - 1367-2630

M1 - 123016

ER -