Unusual hydrogen atom display in solid acids

TL;DR

This paper reports the discovery of dynamically disordered hydrogen atoms in solid acids' crystal structures, proposing a new concept of dynamic twinning to explain this unusual phenomenon.

Contribution

It introduces the concept of dynamic twinning to explain low-occupancy hydrogen atom disorder in superprotonic phases of alkali metal hydrogen sulfates and selenates.

Findings

Observation of low-occupancy hydrogen atoms in electron density maps

Proposal of dynamic twinning as an explanation for the disorder

Identification of unusual hydrogen atom behavior in solid acids

Abstract

Studying crystal structures of superprotonic phases of alkali metal hydrogen sulfates and selenates, a very unusual phenomenon has been revealed. Dynamically disordered hydrogen atoms with low position occupancies are clearly seen in corresponding electron density maps. To explain this effect, an idea about a new type of twinning, dynamic twinning, was proposed and discussed.