The linear regression equation determining a dependence between crystal-nematic mesophase transition temperature, TN, and energy of the torsion deformation, ET, of the nematogene molecules has been obtained on the strength of calculations by the MM2 molecular mechanics method. It has been perfomed this transition occurs on reach such value TNwhich corresponds to the average quantity of the heat kinetic energy <EK> in respect to the two short molecule axes exceeding ET. The methods of consideration of the intermolecular association have been examined.