Peierls Instabilities in Quasi-One-Dimensional Quantum Double-Well Chains

TL;DR

This paper investigates Peierls instabilities in quantum double-well hydrogen-bonded chains, revealing how strong proton-phonon coupling induces insulator transitions and analyzing the effects of transport amplitudes, with relevance to superprotonic systems and hydrogen halides.

Contribution

It provides an analytical study of Peierls instabilities considering proton-phonon interactions and compares theoretical results with experimental pressure effects.

Findings

Large proton-phonon coupling leads to insulator states.

Transport amplitudes significantly influence ground state properties.

Results align with pressure effects observed in experiments.

Abstract

Peierls-type instabilities in quarter-filled ($\bar{n}=1/2$) and half-filled ($\bar{n}=1$) quantum double-well hydrogen-bonded chain are investigated analytically in the framework of two-stage orientational-tunnelling model with additional inclusion of the interactions of protons with two different optical phonon branches. It is shown that when the energy of proton-phonon coupling becomes large, the system undergoes a transition to a various types of insulator states. The influence of two different transport amplitudes on ground states properties is studied. The results are compared with the pressure effect experimental investigations in superprotonic systems and hydrogen halides at low temperatures.