8th Liquid Matter Conference September 6-10, 2011 Wien, Austria ...

Fri 911:10-14:00P1.39The dielectric response of charged liquidsMarcello Sega, 1 Sofia Kantorovich, 2 Axel Arnold, 1 and Christian Holm 11 ICP / University of Stuttgart, Pfaffenwaldring 27, 70569, Stuttgart, Germany2 Ural State University, Ekaterinburg, Russian FederationDielectric spectroscopy is a powerful tool to investigate the dynamical properties of liquids, butthe interpretation of the spectra requires a proper theoretical modeling of diverse relaxation mechanisms,which is often not an easy task. Computer simulations can provide an important contributionin this respect, as it is possible to separate different contributions to the spectra at will. In orderto do so, of course, a consistent scheme for the calculation of the frequency-dependent dielectricresponse of the system is needed: while this task poses no challenge for dipolar fluids, in case ofcharged liquids, like ionic liquids, the usual linear-response expression for the dielectric functionis afflicted by the divergence of the second moment of the dipole vector [1, 2]. A well-defined,convenient expression for the dielectric response which does not require arbitrary separation intofree charges and dipolar contributions can be derived using the microscopic current only. Simulationsresults of salt solutions and model ionic liquids are presented to elucidate the peculiaritiesof the frequency-dependent dielectric response and its static limit. [1] J. M. Caillol, D. Levesque,and J. J. Weis, J. Chem. Phys. 85, 6645 (1986) [2] C. Schröder, M. Haberler, and O. Steinhauser,J. Chem. Phys. 128 134501 (2008)39