Journal ArticleDOI
Effect of environment on hydrogen bond dynamics in liquid water.
Alenka Luzar,David Chandler +1 more
TLDR
It is demonstrated that the long time dynamics of a single hydrogen bond in ambient liquid water is indeed characterized by significant nonexponential relaxation, and this complex relaxation is essentially uncorrelated to the specific bonding patterns near the tagged hydrogen bond.Abstract:
In a series of molecular dynamics calculations we simulate the dynamics of forming and breaking a hydrogen bond in liquid water at room temperature. We show that this dynamics is clearly nonexponential, yet virtually uncorrelated with the fluctuations of neighboring bonds.read more
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Dissertation
From Structure to Thermodynamics with Local Molecular Field Theory
Abstract: Title of dissertation: FROM STRUCTURE TO THERMODYNAMICS WITH LOCAL MOLECULAR FIELD THEORY Richard Charles Remsing III, Doctor of Philosophy, 2013 Dissertation directed by: Professor John D. Weeks Department of Chemistry and Biochemistry Institute for Physical Science and Technology A fundamental goal of statistical mechanics is to connect a description of the intermolecular interactions and the accompanying microscopic structural details of a molecular system to its macroscopic thermodynamic properties. When the interactions between molecular components are treated with sufficient simplicity, as in an ideal gas or a hard sphere fluid for example, the link between structure and thermodynamics can be apparent. In contrast, when both local and non-local interactions are present in the system, competition between the various short and long ranged forces can lead to surprising thermodynamic behaviors as exemplified by the complexities of liquid water. Local molecular field (LMF) theory provides a physically motivated formalism for systematically decomposing the structure and thermodynamics of molecular systems into portions arising from local and non-local interactions. In this thesis, LMF theory is employed to examine the structure and thermodynamics of molecular systems, with a focus on aqueous solutions. LMF-motivated truncations of classical water models are first developed as analysis tools to explore the roles of the local hydrogen bond network, dispersion interactions, and long ranged multipolar interactions in the determination of several anomalous thermodynamic properties of bulk water. This type of analysis is then extended to the study the relative importance of hydrogen bonding and interfacial unbalancing potentials in hydrophobic effects. The underlying ideas of LMF theory are then utilized to study local and non-local interactions in ion solvation. Modifications to classical dielectric continuum theories are explored with a focus on determining the electrostatic potentials inside ionic cores. LMF ideas are then used to develop the concept of a Gaussian test charge. We then argue that this type of test charge is the appropriate generalization of a classical point test charge to probe the dielectric response of molecularly detailed systems and develop an accurate formalism for the description of the dielectric response to such probes. Finally, a LMF theoretic foundation for performing free energy calculations is developed and tested before concluding the thesis with a discussion of future work involving LMF theory. FROM STRUCTURE TO THERMODYNAMICS WITH LOCAL MOLECULAR FIELD THEORY
Journal ArticleDOI
Solvation structure of nanoscopic hydrophobic solutes in supercritical water: Results for varying thickness of hydrophobic walls, solute-solvent interaction and solvent density
TL;DR: In this paper, the effects of varying solute-water interactions and thickness of solute layers on the wetting and dewetting behavior and solvation structures under supercritical conditions have been investigated.
Journal ArticleDOI
Prediction of microscopic structure and physical properties of complex fluid mixtures based on molecular simulation
TL;DR: In this article, the Gibbs free energy of solvation of four organic solutes is calculated for two types of complex fluid mixtures, namely elastomer polymer mixtures and water-1-octanol binary and ternary mixtures.
Journal ArticleDOI
Time-dependent density functional theory study on the excited-state hydrogen-bonding characteristics of polyaniline in aqueous environment.
Yahong Zhang,Yuping Duan,Jin Liu +2 more
TL;DR: It was concluded that all the hydrogen-bonded PANI-H2O complexes were primarily excited to the S1 states with the largest oscillator strength and the orbital transition from the highest occupied molecular orbital to the lowest unoccupied molecular orbital involved intramolecular charge redistribution resulting to increase the electron density of the quinonoid rings.
Journal ArticleDOI
Multiple time scale behaviors and network dynamics in liquid methanol.
TL;DR: The time scales associated with network reorganization dynamics appear to be qualitatively similar in these systems, despite the fact that water and silica both display diffusional anomalies but methanol does not.