The evolution of the phase state of submonolayer films of lithium on the (112) face of tungsten and molybdenum was studied. To do this, 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 vibrations, and the periodic potential of the substrate. The mathematical model effectively reproduces the already known structural features of the adsorbed film. It is shown that the liquid crystal phase is formed as a result of the melting of solid crystals. Long-range order is imposed by substrate potential relief. A binodal was constructed, which defines the area of existence of the p(4x1) structure. Processes leading to a change in the phase state of the adsorbed film were investigated 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.