Absence of proton tunneling during the hydrogen bond symmetrization in $\delta$-AlOOH

Abstract

$\delta$-AlOOH is of significant crystallochemical interest due to a subtle structural transition near 10 GPa from a $P{2}_{1}nm$ to a $Pnnm$ structure, the nature and origin of hydrogen disorder, the symmetrization of the O-H$\cdots$O hydrogen bond and their interplay. We perform a series of density functional theory based simulations in combination with high-pressure nuclear magnetic resonance experiments on $\delta$-AlOOH up to 40 GPa with the goal to better characterize the hydrogen potential and therefore the nature of hydrogen disorder. Simulations predict a phase transition in agreement with our nuclear magnetic resonance experiments at $10-11$ GPa and hydrogen bond symmetrization at $14.7$ GPa. Calculated hydrogen potentials do not show any double-well character and there is no evidence for proton tunneling in our nuclear magnetic resonance data.

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Cited by in corpus (2)

• Probing the state of hydrogen in $\delta$-AlOOH at mantle conditions with machine learning potential
• Ab initio investigation of H-bond disordering in $\delta$-AlOOH