Issue 48, 2011

Examining the robustness of first-principles calculations for metal hydride reaction thermodynamics by detection of metastable reaction pathways

Abstract

First principles calculations have played a useful role in screening mixtures of complex metal hydrides to find systems suitable for H2storage applications. Standard methods for this task efficiently identify the lowest energy reaction mechanisms among all possible reactions involving collections of materials for which DFT calculations have been performed. The resulting mechanism can potentially differ from physical reality due to inaccuracies in the DFT functionals used, or due to other approximations made in estimating reaction free energies. We introduce an efficient method to probe the robustness of DFT-based predictions that relies on identifying reactions that are metastable relative to the lowest energy reaction path predicted with DFT. An important conclusion of our calculations is that in many examples DFT cannot unambiguously predict a single reaction mechanism for a well defined metal hydride mixture because two or more mechanisms have reaction energies that differ by a small amount. Our approach is illustrated by analyzing a series of single step reactions identified in our recent work that examined reactions with a large database of solids [Kim et al., Phys. Chem. Chem. Phys. 2011, 13, 7218].

Graphical abstract: Examining the robustness of first-principles calculations for metal hydride reaction thermodynamics by detection of metastable reaction pathways

Supplementary files

Article information

Article type
Paper
Submitted
02 Aug 2011
Accepted
17 Oct 2011
First published
08 Nov 2011

Phys. Chem. Chem. Phys., 2011,13, 21520-21529

Examining the robustness of first-principles calculations for metal hydride reaction thermodynamics by detection of metastable reaction pathways

K. C. Kim, A. D. Kulkarni, J. K. Johnson and D. S. Sholl, Phys. Chem. Chem. Phys., 2011, 13, 21520 DOI: 10.1039/C1CP22489A

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