Measurement of the 3-D Born-Oppenheimer Potential of a Proton in a Hydrogen Bonded System using Deep Inelastic Neutron Scattering: The Superprotonic Conductor Rb3H(SO4)2

TL;DR

This study measures the three-dimensional Born-Oppenheimer potential of a proton in a hydrogen-bonded superprotonic conductor using Deep Inelastic Neutron Scattering, revealing detailed proton potential surfaces and tunneling characteristics.

Contribution

It introduces a method to extract the proton potential surface in a material directly from neutron scattering data, providing new insights into hydrogen bond dynamics.

Findings

Proton potential has a single minimum along the bond

A saddle point exists off the bond direction for tunneling

Measured potential aligns with phenomenological double Morse models

Abstract

Born-Oppenheimer (BO) potential in any material. The proton potential surfaces in the hydrogen bonded superprotonic conductor Rb3H(SO4)2 are extracted from the momentum distribution measured using Deep Inelastic Neutron Scattering(DINS). The potential has a single minimum along the bond direction, which accounts for the absence of the antiferroelectric transition seen in the deuterated material, and a saddle point off the bond direction for tunneling into the next well with a barrier height of 350 meV. The measured potential is in qualitative agreement with phenomenological double Morse potentials that have been used to describe hydrogen bonds in other systems.