  An interaction potential including chloride anion polarization effects,
constructed from first-principles calculations, is used to examine the
structure and transport properties of a series of chloroaluminate melts. A
particular emphasis was given to the study of the equimolar mixture of
aluminium chloride with 1-ethyl-3-methylimidazolium chloride, which forms a
room temperature ionic liquid EMI-AlCl 4. The structure yielded by the
classical simulations performed within the framework of the polarizable ion
model is compared to the results obtained from entirely electronic
structure-based simulations: An excellent agreement between the two flavors of
molecular dynamics is observed. When changing the organic cation EMI+ by an
inorganic cation with a smaller ionic radius (Li+, Na+, K+), the
chloroaluminate speciation becomes more complex, with the formation of Al2Cl 7-
in small amounts. The calculated transport properties (diffusion coefficients,
electrical conductivity and viscosity) of EMI-AlCl4 are in good agreement with
experimental data.
