Calculation of conformational entropy and free energy of polysilane chain

The conformational entropy S and free energy F were calculated by exact enu meration of polysilane chain up to 23 segments with excluded volume (EV) an d long-range van der Waals (VW) interaction. A nonlinear relation between S EV+VW and chain length n was found though S-EV was found to vary linearly w ith n. We found that the second-order transition temperature of polysilane chain with VW interaction increases with the increase of chain length, whil e that of polysilane chain without VW interaction is chain length independe nt. Moreover, the free energies FEV+VW and F-EV are both linearly related w ith n, and FEV+VW < F-EV for all temperatures.