First sharp diffraction peak in the fragile liquid Ca0.4K0.6(NO3)(1.4)

Molecular-dynamics simulations of the glass former Ca0.4K0.6(NO3)(1.4) (CKN ) have been performed with a polarizable model for the nitrate ion. Polariz ation effects in the anion were included with a fluctuating charge model. C omparison of the Ca-Ca partial radial distribution functions calculated wit h the polarizable model and the rigid ion model counterpart indicates that closer approach of calcium ions is allowed with the polarizable model. Typi cal clusters which an stabilized by ionic polarization are identified in sn apshots of the simulated system. The prepeak or first sharp diffraction pea k observed in the experimental static structure factor, and the associated intermediate-range order, is reproduced in the calculated structure factor provided that polarization is included in the simulation. The polarization effects on the equilibrium structure of this archetypic fragile liquid are compared to previous results on strong ionic liquids.