The subject of the present paper is computer simulation of a-solid and liquid nitrogen, using a Lennard-Jones atom-atom potential and the isothermal-isobaric Monte-Carlo method. Two sets of calculations were performed, both at the same pressure (1 atm) and temperatures (a-solid at 25 and 35.6 K, liquid at 63.15 and 77.35 K). In the first set the molecules are assumed to be rigid, whereas in the...