Crystal structure prediction of LiBeH3 using ab initio total-energy calculations and evolutionary simulations

Chao-Hao Hu; A R Oganov; Y M Wang; H Y Zhou; A Lyakhov; J Hafner

doi:10.1063/1.3021079

Crystal structure prediction of LiBeH3 using ab initio total-energy calculations and evolutionary simulations

J Chem Phys. 2008 Dec 21;129(23):234105. doi: 10.1063/1.3021079.

Authors

Chao-Hao Hu¹, A R Oganov, Y M Wang, H Y Zhou, A Lyakhov, J Hafner

Affiliation

¹ Direction Chimie et Physico-chimie Appliquées, Institut Français du Pétrole, 1 and 4 Av. de Bois-Préau, 92852 Rueil-Malmaison Cedex, France. chaohao.hu@guet.edu.cn

PMID: 19102524
DOI: 10.1063/1.3021079

Abstract

The stable crystal structure of LiBeH(3) is predicted on the basis of ab initio total-energy calculations using density-functional theory and an extended database of candidate structures and using global optimizations based on an evolutionary algorithm. At the level of density-functional theory, a CaSiO(3)_1-type structure with space group P2(1)/c, containing BeH(4) tetrahedra linked in chains, is the ground-state structure of LiBeH(3) (alpha-LiBeH(3)). It is found to be lower in energy than the structures proposed in previous studies. The analysis of the electronic structure shows that alpha-LiBeH(3) is an insulator with a band gap of about 4.84 eV and exhibits strong covalent bonding in the BeH(4) tetrahedral complexes. Calculations at finite temperatures and high pressures suggest that at T=408 K and ambient pressure a structural transition from alpha-LiBeH(3) (CaSiO(3)-type) to a YBO(3)-type structure with space group Cmcm occurs and that at a pressure of 7.1 GPa alpha-LiBeH(3) undergoes a pressure-induced structural transition from the alpha-phase to a MgSiO(3)-type structure with space group C2/c. The calculated enthalpies of formation (-45.36 and -30.12 kJ/mol H(2) without and with zero-point energy corrections) are in good agreement with the experimental result, indicating that LiBeH(3) is a potential hydrogen storage material with low activation barriers for hydrogen desorption.