The heat of sublimation of linear paraffin chains from the crystalline form to the gas at 0°K is calculated from heats of fusion, heats of vaporization, and heat capacities of solid, liquid, and gaseous hydrocarbons. The heat of sublimation, which is defined as the lattice energy of the crystalline phase of linear polyethylene, is 1.84 kcal/mole of CH2groups. The heat of fusion of crystalline linear polyethylene is 0.922 kcal/mole of CH2groups.