THE TRANSITION POINTS IN THE LIQUID-STATE AND THEIR MOLECULAR MODELING

A unified approach leading to the understanding of the liquid state ha s been developed. The liquid state is characterized by the onset of no n-linear anharmonic vibrations at T-g, and is connected with the first appearance of vacancies. The second boundary temperature for the liqu id state ''T-c'' is understood as the temperature at which (as a resul t of an overabundance of holes) the continuous phase can no longer exi st and the ''foamy'' structure of the liquid disintegrates into cluste rs. The p(c) value is connected with the cohesive energy density and a lso depends on Fitter's acentric factor which itself can characterize the type of bonding (local versus dispersed) of the molecule within th e liquid phase. The critical volume of individual compounds seems to b e mainly connected with the high-frequency electronic vibrations of in dividual atoms and their polarizabilities. The critical volume is usua lly about 50-55 times larger than the summation of individual electron ic polarizabilities of the atoms from which the characteristic substan ce is made.