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An Analytical Bond Order Potential for Mg−H Systems
Author(s) -
Zhou Xiaowang,
Kang Shinyoung,
Heo Tae Wook,
Wood Brandon C.,
Stavila Vitalie,
Allendorf Mark D.
Publication year - 2019
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.201800991
Subject(s) - hydrogen storage , molecular dynamics , dehydrogenation , chemistry , hydrogen , thermodynamics , magnesium , crystal structure , metal , gibbs free energy , kinetic energy , chemical physics , computational chemistry , crystallography , catalysis , organic chemistry , physics , quantum mechanics
Magnesium‐based materials provide some of the highest capacities for solid‐state hydrogen storage. However, efforts to improve their performance rely on a comprehensive understanding of thermodynamic and kinetic limitations at various stages of (de)hydrogenation. Part of the complexity arises from the fact that unlike interstitial metal hydrides that retain the same crystal structures of the underlying metals, MgH 2 and other magnesium‐based hydrides typically undergo dehydrogenation reactions that are coupled to a structural phase transformation. As a first step towards enabling molecular dynamics studies of thermodynamics, kinetics, and (de)hydrogenation mechanisms of Mg‐based solid‐state hydrogen storage materials with changing crystal structures, we have developed an analytical bond order potential for Mg−H systems. We demonstrate that our potential accurately reproduces property trends of a variety of elemental and compound configurations with different coordinations, including small clusters and bulk lattices. More importantly, we show that our potential captures the relevant (de)hydrogenation chemical reactions 2H (gas)→H 2 (gas) and 2H (gas)+Mg (hcp)→MgH 2 (rutile) within molecular dynamics simulations. This verifies that our potential correctly prescribes the lowest Gibbs free energies to the equilibrium H 2 and MgH 2 phases as compared to other configurations. It also indicates that our molecular dynamics methods can directly reveal atomic processes of (de)hydrogenation of the Mg−H systems.