Phase Transitions in Anisotropic Submonolayer Adsorbed Films

The study of the evolution of the phase state of submonolayer lithium films on the (112) face of tungsten and molybdenum was conducted. For this purpose, we developed software based on molecular dynamics. The lateral interaction potential takes into account the dipole–dipole repulsion of adatoms, the interaction through the electron gas of the adsorbent due to Friedel oscillations and the periodic potential of the substrate. The mathematical model effectively reproduces already known structural features of the adsorbed film. It is demonstrated that a liquid crystalline phase is formed as a result of the melting of solid crystals. A long-range order is imposed by the potential relief of the substrate. A binodal was constructed, which defines the region of the p(4 х 1) structure existence. The processes leading to a change in the phase state of the adsorbed film were studied at the atomic level. It is shown that the kinetic approach to the study of phase transition processes in two-dimensional (2D) systems does not contradict the basic principles of thermodynamics.