Microscopic calculation of the free energy cost for activated transport in glass-forming liquids

作者：Rabochiy Pyotr^*; Lubchenko Vassiliy

来源：Journal of Chemical Physics, 2013, 138(12): 12A534.

DOI：10.1063/1.4790399

Activated transport in liquids-supercooled liquids in particular-occurs via mutual nucleation of alternative, aperiodic minima of the free energy. Xia and Wolynes [Proc. Natl. Acad. Sci. U. S. A. 97, 2990 (2000)] have made a general argument that at temperatures near the ideal glass transition, the surface penalty for this kind of nucleation is largely determined by the temperature and the logarithm of the size of the vibrational fluctuation of rigid molecular units about the local minimum. Here, we independently show how to estimate this surface tension and, hence, the activation barrier for the activated transport for several actual liquids, using their structure factors and knowledge of the finite-frequency elastic constants. In this estimate, the activation free energy, while depending on the configurational entropy, also depends on the elastic modulus as in the %26quot;shoving%26quot; models. The resulting estimates are however consistent with the estimate provided by Xia andWolynes%26apos; argument near the glass transition and, in addition, reflect the barrier softening effects predicted earlier for fragile substances.

• 出版日期2013-3-28