A Triple Point on the Phase Diagram of a One-component System in the Van der Waals Approximation

In this work, a phase diagram of the neighborhood of the triple point of a one-component system in the van der Waals approximation is constructed. It is shown that this approximation makes it possible to describe the triple point corresponding to the coexistence of three aggregate states of matter – solid, liquid and gaseous. The possibility of using this approximation for triple points of other types is discussed.