Two-dimentional (2D) materials are a dynamic and promising field of research. They have many striking features in a freestanding form. However, their layer-by-layer sequence in the form of Van der Waals (VdW) heterostructures brings even more opportunities for adapting and tuning materials properites. A large number of interesting effects have already been observed for systems based on VdW heterostructure and have to be investigated theoretically. One of the cases of such heterostructures is graphene nanobubbles, consisting of curved graphene layer filled with some substance and attached to a substrate.
In this work, the results of atomistic simulations of the liquid–crystal phase transition of argon, trapped in graphene nanobubbles [1] are presented. The main emphasis is made on the methodology of phase transition modelling, i.e., we propose a technique which aims to avoid metastable states of argon. The scientific contribution of this work consists in the disclosure of how confinement affects phase transition parameters and structural evolution of argon. Calculated results show that provided the same pressures, confined argon melts at temperatures 10–30 K higher, than in case of “free” argon. Also, the sliced structure of the confined liquid argon was detected.
The simulations consisted in heating and cooling processes with no deformational forces using molecular dynamics (MD) method. It was conducted with the large-scale atomic/molecular massively parallel simulator (LAMMPS) software package [2]. The potentials used in the work were: the Tersoff potential for the carbon interaction within graphene sheet, the Lennard-Jones potential for argon–argon and argon–carbon interactions. The argon pressure was calculated with two different approaches to minimize the error of computation of the temperature shift.


[1] Khestanova E, Guinea F, Fumagalli L, Geim A K and Grigorieva I V 2016 Nat. Commun. 7 1–10
[2] S. Plimpton, Journal of computational physics, 1995, 117, 1– 19

Maria Korneva is a 3rd year PhD student at Skoltech working with Prof. Akhatov and Dr. Zhilyaev. Before Skoltech, she got her Bachelor’s and Master’s degrees at MIPT in applied mathematics and physics, Faculty of Molecular and Chemical Physics. Her current research is focused on the study of graphene nanobubbles. The novel results reveal possibility of trapped argon to form sliced structure in liquid state. The future research will concern properties of similar Van der Waals heterostructures, constructed from 2D materials and methodology of their study.