Statistics of Thermal Vibrations

The most important assumptions for the applicability of thermodynamical statistics is the independence of the particles from one another and the absence of interchange effects between them. Boltzmann — as well as Bose- and Fermi-statistics consider individual particles without interaction. In the gaseous state, photons, electrons as well as molecules coexist. In applying these theories to condensed phases, the individual particle is to be considered, according to Schrodingerls, either in a continuous medium otherwise the interaction must be taken into account. 

A free rotating of the CH3-group is hindered by molecular forces caused by the molecular drain AB (Fig. 2). It is less hindered if cross vibrations of the molecular chain take place simultaneously. 

In many cases we can describe the situation by a schema (Fig. 4) showing the potential energy between the positions ( ) and (B ). The improbable conformation (c) is characterized by a distortion of the valence angles and repulsive forces acting on neighboring molecules. The calculations given in the appendix (i) are limited to one space component in the direction between the two possible conformations. 

The probability of the transfer of a molecule from the conformation (B) into a second possible position (S ) will be favored not only by a large amplitude of osdl- 

Segment rotation leading to a chain molecule from Position II to III 

---