Free energy barriers for local hydrogen diffusion in sodium alanates

Sara Bonella
Università di Roma “La Sapienza”

The single sweep approach, recently introduced by Maragliano and Vanden-Eijnden, combines an accelerated dynamics scheme with a radial basis representation to efficiently reconstruct complex free energy landscapes. In this presentation, the approach is combined with ab initio molecular dynamics and brute force histogram calculation to study putative mechanisms for the short range diffusion of hydrogen in sodium alanates. These compounds have attracted considerable interest as potential solid state hydrogen storage materials. The goal of our calculations is to investigate the identity of a mobile species observed in experiments to characterize the first dissociation reaction of the material.

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