Conductivity of molten sodium chloride in an alternating electric field

The conductivity of molten sodium chloride in alternating electric fields of large amplitude for a large range of frequencies, using two types of thermostat was investigated, and compared it to the spectral density of the equilibrium current autocorrelation function. The current correlation function have a negative long-time tail, which makes the imagnicary part of the specytral density negative in a low-frequency range. This result was verified by NEMD simulation in an elecric field of small amplitude E₀=1.22x10⁹ V/m, for which the response was linear with both thermostats in the whole investigated range of frequencies.