Berlin 2015 – scientific programme

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BP: Fachverband Biologische Physik

BP 38: Electrolytes at Interfaces - Stern Layer (focus session, joint CPP/BP/O)

BP 38.9: Talk

Wednesday, March 18, 2015, 17:30–17:45, C 130

Dielectric Response of the Water Hydration Layer and its Application on the Solvation Energy — •Christian Schaaf and Stephan Gekle — University Bayreuth, Bayreuth, Germany

The electric field caused by a charged solute molecule introduced into a dipolar liquid solvent leads to a reorientation of the solvent molecules which is quantified by the solvent’s local dielectric constant.

We calculate this dielectric response function using two different methods; linear response for a system with the explicit solute and theoretical calculations using the wave-vector dependent, non-local bulk permittivity. The good agreement leads to our central result: while the water dielectric constant for a radial field in the hydration layer of spherical solutes is strongly different from bulk water, this difference is not due to significant restructuring of the hydrogen bond network, but can be traced back almost entirely to bulk properties of pure water.

Finally, integrating our dielectric profiles, we calculate the solvation energies for Na⁺, Cl⁻, I⁻, and Cs⁺ and find quantitative agreement with experimental data.