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

Autor(en)

Chao-Hao Hu, Artem Oganov, Y.M. Wang, Huaiying Zhou, Andriy Lyakhov, Juergen Hafner

Abstrakt

The stable crystal structure of LiBeH₃ 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 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(en)

Computergestützte Materialphysik

Externe Organisation(en)

Institut Francais du Petrole (IFP), Eidgenössische Technische Hochschule Zürich, Chinese Academy of Sciences (CAS), Guilin University of Electronic Technology

Journal

Journal of Chemical Physics

Band

129

Anzahl der Seiten

12

ISSN

0021-9606

DOI

https://doi.org/10.1063/1.3021079

Publikationsdatum

2008

Peer-reviewed

Ja

ÖFOS 2012

103015 Kondensierte Materie

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/428bad4d-a98c-4f8e-95b3-3d67102a8429