A PROCEDURE TO QUANTIFY THE SHORT RANGE ORDER OF DISORDERED PHASES

摘要

Determination of the short- and intermediate-range structure of disordered materials is a necessary step to fully understand their properties. Despite of this, no generally accepted procedure exists to date to extract structural information from diffraction data. In this paper we describe a method which enables determination of the short-range structure of disordered molecular phases. This general method is applied to one of the first studied molecular liquids, carbon tetrachloride, and to its plastic phase being able to unravel the so called local density paradox: although molecules are closer in the liquid than in the plastic phase, the density of the former is lower than that of the later. The analysis of the short range order in both phases shows that although the minimal energy configuration allows a closer approach of molecules, it hinders the formation of the face centered cubic long range ordered lattice due to the difficulty of molecules to form stacked structures.