The packing/surface energetics for the initial layer of epitaxially deposited polyethylene on NaCl has been calculated as a function of the total interactive geometry. Three stable packing modes are found. One mode corresponds to the high energy monoclinic packing observed experimentally. The other two forms are not readily identified with any known crystal packing modes although minor geometric alternations in both forms would lead to the familiar orthorhombic packing of polyethylene chains. The computations indicate that the substrate forces induce a strain within the monolayer of chains that results in specific positioning of PE chains over Na + rows.