First-Principles Determination of the Structure of Magnesium Borohydride

Xiang-Feng Zhou, Artem R. Oganov, Guang-Rui Qian, and Qiang Zhu

Phys. Rev. Lett. 109, 245503 – Published 10 December 2012

Abstract

The energy landscape of $Mg ({BH}_{4})_{2}$ under pressure is explored by ab initio evolutionary calculations. Two new tetragonal structures, with space groups $P \bar{4}$ and $I 4_{1} / a c d$ , are predicted to be lower in enthalpy by 15.4 and $21.2 kJ / mol$ , respectively, than the earlier proposed $P 4_{2} n m$ phase. We have simulated x-ray diffraction spectra, lattice dynamics, and equations of state of these phases. The density, volume contraction, bulk modulus, and simulated x-ray diffraction patterns of $I 4_{1} / a c d$ and $P \bar{4}$ structures are in excellent agreement with the experimental results.

Received 2 October 2012

DOI:https://doi.org/10.1103/PhysRevLett.109.245503

Authors & Affiliations

Xiang-Feng Zhou^1,2,*, Artem R. Oganov^2,3, Guang-Rui Qian², and Qiang Zhu²

¹School of Physics and Key Laboratory of Weak-Light Nonlinear Photonics, Nankai University, Tianjin 300071, China
²Department of Geosciences, Department of Physics and Astronomy, Stony Brook University, Stony Brook, New York 11794, USA
³Geology Department, Moscow State University, Moscow 119992, Russia