2015/01/08 by Susmita Roy, Roy, Susmita, S. Yashonath +4
Chemical Engineering · Chemistry · Physics and Astronomy · #Advanced Physical and Chemical Molecular Interactions #Chemical Physics (physics.chem-ph) #Electrostatics and Colloid Interactions #FOS: Physical sciences #Soft Condensed Matter (cond-mat.soft) #Spectroscopy and Quantum Chemical Studies #Statistical Mechanics (cond-mat.stat-mech) #Thermodynamic properties of mixtures
paper · pdf · doi:10.48550/arxiv.1501.01845
openalex publication_date 2015/01/08 · openalex created_date 2022/08/30 · openalex updated_date 2026/07/28
A self-consistent mode coupling theory (MCT) with microscopic inputs of\nequilibrium pair correlation functions is developed to analyze electrolyte\ndynamics. We apply the theory to calculate concentration dependence of (i) time\ndependent ion diffusion, (ii) dynamic structure factor of the constituent ions,\nand (iii) ion solvation dynamics in electrolyte solution. Brownian dynamics\n(BD) with implicit water molecules and molecular dynamics (MD) method with\nexplicit water are used to check the theoretical predictions. The time\ndependence of ionic self-diffusion coefficient and the corresponding dynamic\nstructure factor evaluated from our MCT approach show quantitative agreement\nwith early experimental and present Brownian dynamic simulation results. With\nincreasing concentration, the dispersion of electrolyte friction is found to\noccur at increasingly higher frequency, due to the faster relaxation of the ion\natmosphere. The wave number dependence of total dynamic structure factor\nF(k,t), exhibits markedly different relaxation dynamics at different length\nscales. At small wave numbers, we find the emergence of a step-like relaxation,\nindicating the presence of both fast and slow time scales in the system. Such\nbehaviour allows an intriguing analogy with temperature dependent relaxation\ndynamics of supercooled liquids. We find that solvation dynamics of a tagged\nion exhibits a power law decay at long times- the decay can also be fitted to a\nstretched exponential form. The emergence of the power law in solvation\ndynamics has been tested by carrying out long Brownian dynamics simulations\nwith varying ionic concentrations. This solvation time correlation and ion-ion\ndynamic structure factor indeed exhibits highly interesting, non-trivial\ndynamical behaviour at intermediate to longer times that require further\nexperimental and theoretical studies.\n