ISSN:
1089-7690
Source:
AIP Digital Archive
Topics:
Physics
,
Chemistry and Pharmacology
Notes:
The supposedly very simple system of a saturated solution of ZnBr2 in water exhibits unusually complex and therefore interesting structural behavior. Motivated by this, Mager did a detailed x-ray diffraction study (Th. Mager, PhD. thesis, Universität Würzburg, 1991), and we performed a long molecular dynamics (MD) simulation—using potential parameters from the general purpose GROMOS force field—of such a solution, which can be grossly characterized by the formula ZnBr2⋅3H2O. We start by calculating those properties that are directly accessible through the experiment from the MD simulation, in order to validate the physical relevance of the simulation. Seeing that the simulation delivers results that are compatible with those of the experiment, we proceed by analyzing the MD simulation in much more detail according to the static and dynamic structure of the system, thereby gaining insight into the structural behavior of ZnBr2⋅3H2O that is very difficult, if at all possible, to get from experimental studies. To this end we use the Voronoi algorithm to define coordination shells around atoms and ions in ZnBr2⋅3H2O. We study the time averaged as well as the time-resolved geometry and composition of these coordination shells and find that octahedral coordination of Zn2+ ions is the dominant geometry in ZnBr2⋅3H2O, and that these octahedra are remarkably stable (after 1 ns only 10% decayed). We further find evidence for polymerlike Zn2+ chains, where O atoms of water and Br− ions connect the Zn2+ ions. © 1996 American Institute of Physics.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.471405
