Heat capacity at the glass transition

A fundamental problem of glass transition is to provide a quantitative and microscopic explanation of the heat-capacity jump at the glass transition temperature Tg. Similar problems are also common to other disordered systems, including spin glasses. We propose that the jump of heat capacity at Tg takes place as a result of the change of the liquid's elastic, vibrational, and thermal properties. In this theory, we discuss time-dependent effects of glass transition, and identify three distinct regimes of relaxation. Our approach explains a widely observed logarithmic increase of Tg with the quench rate and correlation of the heat-capacity jump with liquid fragility.