Suggested mechanisms responsible for liquid-crystalline ordering include non-spherical excluded volume effects, anisotropic attraction forces and flexibility. It has been shown using hard-core models that non-spherical excluded volume effects are the essential factor and can qualitatively explain the phenomenology of the problem. However, the simulation of hard-core models is technically demanding. A simpler and more direct alternative is to use a model with a soft-core site-site potential. We employ here a system of molecules composed of a few (11) atoms, constrained to form a multilinear molecule, and in mutual interaction via a continuous repulsive site-site potential of the formr-12. Our results show that such a model is capable of exhibiting nematic and smectic liquid-crystal phases.