Intermolecular forces and the internal pressure of liquids

The problem of the introduction of the term internal pressure from the standpoint of intermolecular forces is solved. It is shown that internal pressure is created by the macrosystem average force field of the structural units of a liquid. Internal pressure is shown to be not an energy characteristic, but a macrosystem average force parameter of the interaction between the structural units of a liquid phase system, although it has the energy density dimension, [J/m 3 ].