The athermal lattice model in which elongated rigid molecules are simulated by rows of consecutive sites is generalized so as to include an attractive segmentndash;segment interaction energymdash;egr;. Thus a distinction is made between a liquidlike phase and a supercritical gas phase. The model is solved in the Bethendash;di Marzio and in the quasichemical approximation. The presence of such an attractive interaction leads to a reasonablep,Tdiagram of state providedr=4 or 5 in three or six dimensions. For longer rods, only the phase transition from the supercritical gas with very large volume changes is obtained already forrquest;6.
展开▼