Dresden 2017 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 37: Fluids and Glasses I

CPP 37.1: Vortrag

Mittwoch, 22. März 2017, 10:15–10:30, ZEU 255

Effects of the molecular polarity on the structural and dynamical properties of liquid silica — •Elvira Pafong and Barbara Drossel — Institut für Festkörperphysik, Technische Universität Darmstadt

Silica is a network-forming liquid that shares many properties with water. Both liquids are polar, which leads to directional bonds and complex structural and dynamical features. In particular, liquid silica undergoes a transition from a strong to a fragile glass former, comparable to the transition from a high-density liquid (HDL) to a low-density liquid (LDL) reported in water. Here, we investigate the effect of the molecular polarity on the structure and dynamics of liquid silica using molecular dynamics simulations. We modify polarity by changing the partial charges assigned to each atom. We find that the glass forming ability of liquid silica is enhanced by an increase of the partial charges of up to +20 % . The temperature corresponding to the maximum or the minimum in density, the average tetrahedral order parameter as well as the correlation times increase also. Interestingly, when the partial charges are increased further to +30 % , a fifth atom enters the first neighbouring shell for temperatures above 4000 K, resulting in a structure that is locally less ordered and therefore in less pronounced anomalies.