The thermodynamic properties of amorphous polymeric nytrogen are analyzed theoretically basing on free energy expansion. An approach allowing estimating Helmholtz free energy of high-pressure disordered
condensed phases of nitrogen is proposed. The approach is based on expansion of the excess entropy on interatomic correlations and tested on existing Monte Carlo simulation data. Some specific problems arising on this way and their possible solutions are discussed.
PACS: 65.20.De General theory of thermodynamic properties of liquids, including computer simulation; PACS: 65.20.Jk Studies of thermodynamic properties of specific liquids; PACS: 64.30.Jk Equations of state of nonmetals.
Key words: hign-pressure phase, polymeric phases, Monte Carlo simulation.