STUDIES OF SOLVATED ION DYNAMICS
Abstract
Results of molecular dynamics calculations of dilute aqueous solutions of Li('+), Na('+), K('+), F('-) and Cl('-) are reported. The concepts and calculational methods of molecular dynamics and MTGLE theory {S. A. Adelman, J. Chem. Phys. 73, 3145 (1980)} was applied to gain a detailed understanding at the molecular level of single ion mobility in hydrogen-bonded solvents like water and of the influence of the solvent motion on the ion solute dynamics. Results from our simulations together with experimental results are analyzed to explain these basic questions of dynamic molecular solvation effect on ion solute motion in aqueous solutions. The molecular time-scale generalized Langevin (MTGLE) theory is used to investigate this dynamic ion solvation problem. Simple MTGLE classical trajectory modelling method is found to reliably describe the highly correlated ion-solvent motion in these strong force systems. The computed parameters of the MTGLE equation of motion are in good agreement with experiment results. Correlation of these calculated quantities with available structure and energetics results of dilute aqueous solutions of Li('+), Na('+), K('+), F('-), and Cl('-) provides useful physical insights and it also verifies the physical foundation of the MTGLE theory. This link between the MTGLE basic quantities ((omega)(,e(,0))('2), (omega)(,c(,1))('4)) and the structure and energetic results for these strong solvation solutions together with the MTGLE modelling method permit one to conveniently and reliably predict the dynamics of ion solvation in aqueous solutions of large ions such as NH(,4)('+), Rb('+), Cs('+), Br('-), I('-) from the calculated results for smaller alkali metal and halide ions (Li('+), Na('+), K('+), F('-) and Cl('-)).(') Also the molecular dynamics method together with the generalized Langevin (MTGLE) theory are used to study the solvation of dilute aqueous solution of zinc ion. Good agreements with experiments are obtained for structural and dynamical results. The MTGLE trajectory modelling method is found to conveniently and reliably describe the zinc ion solvation dynamics in dilute aqueous solution. Correlation of the basic MTGLE quantity ((omega)(,e(,0))('2)) with the structural properties of dilute aqueous solutions of alkali metal and halide ions and zinc ion is used to give a fair prediction of the (omega)(,e(,0))('2) values for other divalent transition-metal ions in aqueous solution. These values are favorably compared with experimental far-infrared band parameters.
Degree
Ph.D.
Subject Area
Chemistry
Off-Campus Purdue Users:
To access this dissertation, please log in to our
proxy server.