title: Crystal structure prediction of LiBeH3 using ab initio total-energy calculations and evolutionary simulations.
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.
authors.affiliation: 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
authors.forename: Chao-Hao
authors.initials: CH
authors.lastname: Hu
authors.forename: A R
authors.initials: AR
authors.lastname: Oganov
authors.forename: Y M
authors.initials: YM
authors.lastname: Wang
authors.forename: H Y
authors.initials: HY
authors.lastname: Zhou
authors.forename: A
authors.initials: A
authors.lastname: Lyakhov
authors.forename: J
authors.initials: J
authors.lastname: Hafner