Benzene adsorption at the aqueous (0 1 1) α-quartz interface: is surface flexibility important?

Abstract

Atomistic simulations of molecular adsorption onto inorganic substrates under aqueous conditions can be used to guide the rational design of new materials, fabricated using biomimetic methods. The success of such work depends critically on the model used. Here, we investigate the impact of using a rigid structural model of the (0 1 1) α-quartz surface, over a fully flexible model, on the calculated free energy change in the adsorption of a single molecule of benzene (a simple analogue of the amino acid phenylalanine) from liquid water. Subtle differences in the mobility of the adsorbate close to the surface result in the free energy of adsorption being overestimated by the rigid model, relative to the fully flexible case. Moreover, we find that the distribution of bound configurations of the adsorbate at their respective free energy minima is different between the two models.

Keywords::

• molecular simulation
• adsorption
• interfaces
• potential of mean force

Acknowledgements

The authors gratefully acknowledge the computing facilities of the Centre for Scientific Computing, University of Warwick and Prof. P. Mark Rodger for helpful discussions. LBW thanks the EPSRC for DTA studentship funding. This work was supported by EPSRC Programme Grant (EP/I001514/1) ‘Hard-Soft Matter Interfaces; From Understanding to Engineering’. This Programme Grant funds the Materials Interface with Biology (MIB) consortium. T.R.W. thanks VESKI for an Innovation Fellowship.