Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

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 Ciacchi^2,3 — 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.