Ion–ion and ion–water aggregations and dielectric response of aqueous solutions of Li₂SO₄: molecular dynamic simulations study

Abstract

The dielectric properties of Li₂SO₄ aqueous solutions are studied using the method of molecular dynamic (MD) simulations. The dielectric response is computed for solutions with concentrations between 0.001 and 0.071 mole fraction of salt in the temperature range of 288 to 348 K. Computed values of the static dielectric constant and effective (weighted average) relaxation time are compared with available experimental data. The distributions of dielectric relaxation times are obtained by the decomposition of dipole moment autocorrelation functions (ACF) into a series of single exponentials in the time domain. The distributions of ion–ion and ion–water aggregations in concentrated solutions are computed and their connections to the low frequency modes observed in experimental dielectric spectra are examined. The nature of anomalous (different from single-exponential) dielectric relaxation in Li₂SO₄ aqueous solutions is discussed.

Keywords:

• microwave spectra
• dielectric relaxation
• electrolyte solutions
• molecular dynamics simulations