STRUCTURAL AND DYNAMICAL HETEROGENEITY OF LIQUIDS
George G. Malenkov
Frumkin Institute of Physical Chemistry and Electrochemistry of Russian Academy of Sciences, http://www.phyche.ac.ru/
Moscow 119071, Russian Federation
Received January 22, 2020; peer reviewed February 05, 2020; accepted February 10, 2020
Brief review of the development of the ideas about the heterogeneity is given. In our works it is meant that structural heterogeneity is the non-uniform space distribution of the particles (atoms or molecules) with similar values of the parameters which characterize their surroundings. Volumes of the Voronoi polyhedra (VVP) built around the particular particle, tetrahedricity index T (for water) and potential energy (Ep) of the molecules or atoms were chosen as such parameters. It was shown that molecules the similar (large or small) values of T, VVP and Ep group together often forming ramifying clusters. Structural heterogeneity – grouping of the atoms with similar values of VVP was found for computer models of liquid argon. Dynamical heterogeneity is manifested in different mobility of the molecules with different values of the parameters which characterize their environment. The less trivial dynamical heterogeneity is connected with the fact that the molecules joint by the long-living hydrogen bonds form the clusters which move as single entities. The study of such clusters led us to the investigation of the collective motions in liquids. We found in the course of these works that in liquids there are regions of the space in which the molecules on the average move in the same direction. The size of these regions is more than ten nanometers and they are well manifested if we follow the system during time interval of the order of 100 ps. This also can be regarded as a peculiar dynamical heterogeneity of liquids.
: Voronoi polyhedron, tetrahedrality index, clusters, hydrogen bonds, argon, computer simulation
, 2020, 12(1):29-38.
Full-text electronic version of this article - web site http://en.rensit.ru/vypuski/article/312/12(1)29-38e.pdf