Structure of ionic liquids and concentrated electrolytes from a mesoscopic theory

Recently, underscreening in concentrated electrolytes was discovered experiments and confirmed simulations theory. It found that the correlation length of charge-charge correlations, λs, satisfies scaling relation λs/λD∼(a/λD)n, where λD is Debye screening a ionic diameter. However, different values n were studies. In this work we solve puzzle within mesocopic theory yielded = 3 agreement with experiments, but only very high densities ions considered [A. Ciach O. Patsahan, J.Phys.: Condens. Matter 33, 37LT01 (2021)]. Here apply to broader range density find above can yield fair approximation for λs/λD ranges a/λD. The experimentally holds 2<a/λD<4, same reduced length. For smaller a/λD, 2 obtained earlier several simulation theoretical studies, still closer Kirkwood line obtain 1.5 also predicted works. follows from our (i.e. λs proportional ions) when variance local charge large, times Bjerrum Detailed derivation presented.