Berlin 2012 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 45: Solid / liquid interfaces I
O 45.2: Vortrag
Mittwoch, 28. März 2012, 10:45–11:00, A 060
Ab-initio derived force-field parameters for molecular dynamics simulations of deprotonated amorphous-SiO2/water interfaces — •Anke Butenuth1, Gianpietro Moras1, and Lucio Colombi Ciacchi2,3 — 1Fraunhofer Institute for Mechanics of Materials IWM, Freiburg — 2Hybrid Materials Interfaces Group, BCCMS, Bremen — 3Fraunhofer Institute for Manufacturing Technology and Advanced Materials IFAM, Bremen
Due to its importance for many technologically relevant materials, a large research effort has been devoted to the SiO2/water interface, where work on the theoretical side is based on both quantum-mechanical and classical atomistic methods. However, most of theses studies consider neutral silica surfaces and are, due to the low isoelectric point of silica, only valid under strong acidic conditions.
We present a force field for molecular dynamics simulations of interfaces between natively deprotonated amorphous SiO2 surfaces and liquid water, to be used in combination with standard biomolecular force fields. The extent of negative charge delocalisation in the solid that follows the deprotonation of terminal silanol groups is revealed by extensive Bader analysis of electronic densities computed by Density Functional Theory (DFT). The absolute charge values in our force field are determined from best-fitting to the electrostatic potential computed ab-initio (ESP charges).
Our proposed parameter set is found to reproduce the energy landscape of single water molecules over neutral and deprotonated amorphous SiO2 surfaces.