Abstract
A general lattice-model partition function for condensed phases with partial or total positional ordering (in one to three dimensions) as well as orientational ordering of the molecules in the system is presented. Each molecule is composed of a rigid core and one or two semiflexible tails and has site-site hard repulsive intermolecular interactions. This general model can be applied to a number of special cases, one of which is presented in the following paper.