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

Author(s): Chao-Hao Hu, Artem Oganov, Y.M. Wang, Huaiying Zhou, Andriy Lyakhov, Juergen Hafner
Abstract: The stable crystal structure of LiBeH₃is 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 CaSiO₃_1-type structure with space group P2₁/c, containing BeH₄ tetrahedra linked in chains, is the ground-state structure of LiBeH₃ (α-LiBeH₃). It is found to be lower in energy than the structures proposed in previous studies. The analysis of the electronic structure shows that α-LiBeH₃ is an insulator with a band gap of about 4.84 eV and exhibits strong covalent bonding in the BeH₄ tetrahedral complexes. Calculations at finite temperatures and high pressures suggest that at T=408 K and ambient pressure a structural transition from α-LiBeH₃ (CaSiO₃-type) to a YBO3-type structure with space group Cmcm occurs and that at a pressure of 7.1 GPa α-LiBeH₃ undergoes a pressure-induced structural transition from the α-phase to a MgSiO₃-type structure with space group C2/c. The calculated enthalpies of formation (−45.36 and −30.12 kJ/mol H₂ without and with zero-point energy corrections) are in good agreement with the experimental result, indicating that LiBeH₃ is a potential hydrogen storagematerial with low activation barriers for hydrogen desorption.
Organisation(s): Computational Materials Physics
External organisation(s): Institut Francais du Petrole (IFP), Eidgenössische Technische Hochschule Zürich, Chinese Academy of Sciences (CAS), Guilin University of Electronic Technology
Journal: Journal of Chemical Physics
Volume: 129
No. of pages: 12
ISSN: 0021-9606
DOI: https://doi.org/10.1063/1.3021079
Publication date: 2008
Peer reviewed: Yes
Austrian Fields of Science 2012: 103015 Condensed matter
Portal url: https://ucrisportal.univie.ac.at/en/publications/crystal-structure-prediction-of-libeh3-using-ab-initio-totalenergy-calculations-and-evolutionary-simulations(428bad4d-a98c-4f8e-95b3-3d67102a8429).html