2024--Kalika-E-B-Verkhovtsev-A-V-Maslov-M-M-et-al--Ni-Cl

Abstract: A computational approach combining dispersion-corrected density functional theory (DFT) and classical molecular dynamics is employed to characterize the geometrical and thermomechanical properties of a recently proposed 2D transition metal dihalide NiCl₂. The characterization is performed using a classical interatomic force field whose parameters are determined and verified through the comparison with the results of DFT calculations. The developed force field is used to study the mechanical response, thermal stability, melting and solidification of a NiCl₂ monolayer on the atomistic level of detail. The 2D NiCl₂ sheet is found to be thermally stable at temperatures below its melting point of ~695 K. At higher temperatures, several subsequent structural transformations of NiCl₂ are observed, namely a transition into a porous 2D sheet and a 1D nanowire. The MD simulations of NiCl₂ cooling show that the molten NiCl₂ system solidifies into an amorphous porous 2D structure at T ~450 K. The resulting structure has lower cohesive energy with respect to the initial 2D sheet. The computational methodology presented through the case study of NiCl₂ can also be utilized to study the properties of other novel 2D materials, including recently synthesized NiO₂, NiS₂, and NiSe₂.