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

Tue 611:23-14:00P2.41Static dielectric constant of polarizable models fromsimulationsJiri Kolafa 11 Institute of Chemical Technology, Prague, Department of Physical Chemistry,Technicka 5 166 28, Praha 6, Czech RepublicTwo sources of inaccuracies in standard determination of static dielectric constant in simulationsare analyzed: The fluctuation formulas applied to models with large polarizability in tin-foil boundaryconditions may suffer from large polarization so that the dielectric response is no longer linear.A remendy is to decrease the dielectric constant of the surrounding continuum. The high-frequency(i. e. , caused directly by instantaneous polarizability) component of the dielectric constant is commonlyapproximated by the Clausius-Mossotti formula. This may become a source of inaccuracyif the surrounding continuum has a low dielectric constant as well as for models with nonlinearpolarizability. A remendy is to determine the high-frequency response directly in simulations byusing an external field. Theoretical analysis is accompanied by simulations in the Ewald boundaryconditions using both the fluctuation formulas and external electric field method. The systemsstudied include the Dang-Chang (1997) model of water and an fcc crystal of polarizable dipolardiatomics.41