Hodge Stuart R, Corcelli Steven A, Berg Mark A
Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, USA.
Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, USA.
J Chem Phys. 2021 Jul 14;155(2):024123. doi: 10.1063/5.0053424.
Solvation dynamics in ionic liquids show features that are often associated with supercooled liquids, including "stretched" nonexponential relaxation. To better understand the mechanism behind the stretching, the nonlinear mode-correlation methods proposed in Paper I [S. R. Hodge and M. A. Berg, J. Chem. Phys. 155, 024122 (2021)] are applied to a simulation of a prototypical ionic liquid. A full Green's function is recovered. In addition, specific tests for non-Gaussian dynamics are made. No deviations from Gaussian dynamics are found. This finding is incompatible with rate heterogeneity as a cause of the nonexponential relaxation and appears to be in conflict with an earlier multidimensional analysis of the same data. Although this conflict is not resolved here, this work does demonstrate the practicality of mode-correlation analysis in the face of finite datasets and calculations.
