Computational Evidence for the Crucial Role of Dipole Cross-Correlations in Polar Glass-Forming Liquids

It is commonly believed that the dipole-diploe cross-correlations do not contribute to the total dipole correlation function, which is directly probed in the Dielectric Spectroscopy experiment. However, our study of the dipole-dipole correlations obtained from the molecular dynamics simulations for strongly and weakly polar model liquids sheds new light on the above conviction. The obtained results indicate that the cross-correlations' contribution to the system's total dipole moment correlation function is negligible only for weakly polar liquids. In contrast, the cross-correlations term dominates over the self-correlations term for the examined strongly polar liquid. Consequently, our studies strongly give fundaments for the suggested in the literature correlation between the shape of the dielectric spectra and the value of the dipole moments (Phys. Rev. Lett 116, 025702, 2016) well as they support the interpretation of the dielectric spectra nature of glass-forming liquids recently proposed by Pabst et al. (J.Phys. Chem. Lett. 12, 3685, 2021)