Molecular hydrogen isotopes adsorbed on krypton-preplated graphite: Quantum Monte Carlo simulations

TL;DR

This study uses quantum Monte Carlo simulations to analyze the structural and energetic properties of hydrogen isotopes adsorbed on krypton-preplated graphite, revealing stable solid films and the absence of superfluidity, with evidence of a domain wall fluid.

Contribution

First theoretical investigation of hydrogen isotope adsorption on krypton-preplated graphite using quantum Monte Carlo methods, including substrate corrugation effects.

Findings

Adsorbed films are thermodynamically stable solids.

No superfluidity observed due to lack of quantum exchanges.

Evidence of a stable domain wall fluid at low temperature.

Abstract

Adsorption of ortho-deuterium and para-hydrogen films on a graphite substrate, pre-plated with a single atomic layer of krypton, is studied theoretically by means of quantum Monte Carlo simulations at low temperature. Our model explicitly includes substrate corrugation. Energetic and structural properties of these adsorbed films are computed for a range of hydrogen coverages. Thermodynamically stable adsorbed films are solid, with no clear evidence of any liquid-like phase. Quantum exchanges of ortho-deuterium and para-hydrogen are essentially absent in this system, down to zero temperature; consequently, this system displays no superfluidity in this limit. Our simulations provide evidence of a stable domain wall fluid at low temperature, consistently with recent experimental observations.