Title: Mutual effect of charge- and number-density correlations in ionic liquids and concentrated electrolytes
Author(s):

	O. Patsahan (Institute for Condensed Matter Physics of the National Academy of Sciences of Ukraine, 79011, Lviv, Ukraine),
	A. Ciach (Institute of Physical Chemistry, Polish Academy of Sciences, 01-224 Warszawa, Poland)

Correlation functions in concentrated ionic systems are studied within the mesoscopic theory on the level of the Gaussian approximation. The previously neglected fluctuation contribution to the inverse charge-charge correlation function is taken into account to verify the accuracy of the previous results. We calculate the correlation lengths and the amplitudes and show that the fluctuation contribution does not lead to significant changes of the results. We also derive necessary conditions for the presence of both, the oscillatory and the monotonic decays of the charge-charge correlations that must be satisfied by the noncoulombic contributions to the inverse charge-charge correlation function. On the level of the Gaussian approximation, these conditions are not satisfied. Extension of the theory beyond the Gaussian approximation is necessary to verify if the asymptotic decay of the charge-charge correlations is monotonic or oscillatory, as suggested by the surface force apparatus or by the SAXS experiments, respectively.

Key words: charge-charge correlation function, correlation lengths, concentrated electrolytes, mesoscopic theory

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