Download or read book Structural and Vibrational Properties of Liquid Water and Aqueous Solutions from First Principles Molecular Dynamics written by Cui Zhang and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We carried out a series of ab initio molecular dynamics simulations of liquid water and simple ions in water using density functional theory (DFT). Our study had a two-fold objective: (i) establish which level of ab-initio DFT is appropriate to describe not only the structure of water, but also its vibrational, electronic and some of its thermodynamic properties; (ii) interpret experimental data available for infrared spectra (IR) of the pure liquid and liquid solutions. We first studied IR spectra of water using semilocal functionals. We showed that intermolecular dipolar correlations play a key role in determining the complex shape and width of the IR stretching band and those correlations are long-ranged, extending to the second coordination shell. Using a molecular orbital picture, we identified specific features of the band arising from correlations of electronic contributions to the IR activities. These features are robust and do not depend on the functional used in our simulations. The IR spectra of liquid water obtained with the hybrid functional PBE0 yielded a much better agreement with experimental results than a semilocal functional description (PBE). Such an improved description stems from a two-fold effect: a more accurate account, at the PBE0 level of theory, of the vibrational properties of the water monomer and dimer, and an underlying structural model for the liquid with a smaller number of hydrogen bonds and oxygen coordination than those obtained with semilocal functionals. Also with van der Waals density functionals, liquid water displays a hydrogen-bonded network less tightly bound than when using semilocal and hybrid functionals, and yielded IR spectra in good agreement with experiment. However, PBE0 greatly improves the description of water electronic properties (e.g. the quasi-particle gap), while van der Waals functionals yielded results similar to PBE. In spite of improvements in the description of the structural and vibrational properties of water found when using hybrid or van der Waals functionals, our study of the entropy of the liquid indicated that in the vicinity of room temperature and at experimental equilibrium density, all functionals severely underestimate the total entropy and the liquid exhibits a degree of tetrahedral order higher than in experiment. In the case of simple solutions, we focused on anions that are technically more demanding to simulate than cations and in particular on the chloride ion. Compared with the pure liquid, we found an overall softening of the hydrogen bonding structure in the chloride solution, with a smaller average dipole moment of water molecules and an increased number of broken or distorted hydrogen bonds. The ion effects on the hydrogen bonding network are significant in the first chloride solvation shell and become weak beyond that, although non-negligible. Overall, our findings represent a significant step forward in the theoretical modeling of water from first principles, as one may extend the framework adopted here with hybrid or van der Waals functionals to other aqueous environments, such as water under confinement or in contact with surfaces.

Download or read book Ab Initio Molecular Dynamics written by Dominik Marx and published by Cambridge University Press. This book was released on 2009-04-30 with total page 503 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ab initio molecular dynamics revolutionized the field of realistic computer simulation of complex molecular systems and processes, including chemical reactions, by unifying molecular dynamics and electronic structure theory. This book provides the first coherent presentation of this rapidly growing field, covering a vast range of methods and their applications, from basic theory to advanced methods. This fascinating text for graduate students and researchers contains systematic derivations of various ab initio molecular dynamics techniques to enable readers to understand and assess the merits and drawbacks of commonly used methods. It also discusses the special features of the widely used Car–Parrinello approach, correcting various misconceptions currently found in research literature. The book contains pseudo-code and program layout for typical plane wave electronic structure codes, allowing newcomers to the field to understand commonly used program packages and enabling developers to improve and add new features in their code.

Download or read book Structural Dynamics in Complex Liquids Studied with Multidimensional Vibrational Spectroscopy written by and published by . This book was released on 2013 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: The development of new sustainable energy sources is linked to our understanding of the molecular properties of water and aqueous solutions. Energy conversion, storage, and transduction processes, particularly those that occur in biology, fuel cells, and batteries, make use of water for the purpose of moving energy in the form of charges and mediating the redox chemistry that allows this energy to be stored as and released from chemical bonds. To build our fundamental knowledge in this area, this project supports work in the Tokmakoff group to investigate the molecular dynamics of water's hydrogen bond network, and how these dynamics influence its solutes and the mechanism of proton transport in water. To reach the goals of this grant, we developed experiments to observe molecular dynamics in water as directly as possible, using ultrafast multidimensional vibrational spectroscopy. We excite and probe broad vibrational resonances of water, molecular solutes, and protons in water. By correlating how molecules evolve from an initial excitation frequency to a final frequency, we can describe the underlying molecular dynamics. Theoretical modeling of the data with the help of computational spectroscopy coupled with molecular dynamics simulations provided the atomistic insight in these studies.

Download or read book The Structure and Properties of Water and Aqueous Solutions written by J. A. Barker and published by . This book was released on 1972 with total page 48 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Properties of Liquid Water and Solvated Ions Based on First Principles Calculations written by Lixin Zheng and published by . This book was released on 2018 with total page 177 pages. Available in PDF, EPUB and Kindle. Book excerpt: Water is of essential importance for life on earth, yet the physics concerning its various anomalous properties has not been fully illuminated. This thesis is dedicated to the understanding of liquid water from aspects of microscopic structures, dynamics, electronic structures, X-ray absorption spectra, and proton transfer mechanism. This thesis use the computational simulation techniques including density functional theory (DFT), ab initio molecular dynamics (AIMD), and theoretical models for X-ray absorption spectra (XAS) to investigate the dynamics and electronic structures of liquid water system. The topics investigated in this thesis include a comprehensive evaluation on the simulation of liquid water using the newly developed SCAN meta-GGA functional, a systematic modeling of the liquid-water XAS using advanced ab initio approaches, and an explanation for a long-puzzling question that why hydronium diffuses faster than hydroxide in liquid water. Overall, significant contributions have been made to the understanding of liquid water and ionic solutions in the microscopic level through the aid of ab initio computational modeling.

Download or read book Linear and Non linear Vibrational Spectroscopy of Water and Aqueous Solutions written by Jordan R. Schmidt and published by . This book was released on 2006 with total page 196 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Structure and Dynamics of Solutions written by H. Ohtaki and published by Elsevier. This book was released on 2013-10-22 with total page 361 pages. Available in PDF, EPUB and Kindle. Book excerpt: Recent advances in the study of structural and dynamic properties of solutions have provided a molecular picture of solute-solvent interactions. Although the study of thermodynamic as well as electronic properties of solutions have played a role in the development of research on the rate and mechanism of chemical reactions, such macroscopic and microscopic properties are insufficient for a deeper understanding of fast chemical and biological reactions. In order to fill the gap between the two extremes, it is necessary to know how molecules are arranged in solution and how they change their positions in both the short and long range. This book has been designed to meet these criteria. It is possible to develop a sound microscopic picture for reaction dynamics in solution without molecular-level knowledge of how reacting ionic or neutral species are solvated and how rapidly the molecular environment is changing with time. A variety of actual examples is given as to how and when modern molecular approaches can be used to solve specific solution problems. The following tools are discussed: x-ray and neutron diffraction, EXAFS, and XANES, molecular dynamics and Monte Carlo computer simulations, Raman, infrared, NMR, fluorescence, and photoelectron emission spectroscopic methods, conductance and viscosity measurements, high pressure techniques, and statistical mechanics methods. Static and dynamic properties of ionic solvation, molecular solvation, ion-pair formation, ligand exchange reactions, and typical organic solvents are useful for bridging the gap between classical thermodynamic studies and modern single-molecule studies in the gas phase. The book will be of interest to solution, physical, inorganic, analytical and structural chemists as well as to chemical kineticists.

Download or read book Molecular Dynamics Simulation Studies of Liquid Water and Aqueous Ionic Solutions written by James Edward Roberts and published by . This book was released on 1995 with total page 358 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Molecular Theory of Water and Aqueous Solutions The role of water in protein folding self assembly and molecular recognition written by Arieh Ben-Naim and published by World Scientific. This book was released on 2009 with total page 482 pages. Available in PDF, EPUB and Kindle. Book excerpt: "The aim of this book is to explain the unusual properties of both pure liquid water and simple aqueous solutions, in terms of the properties of single molecules and interactions among small numbers of water molecules. It is mostly the result of the author's own research spanning over 40 years in the field of aqueous solutions."--Jacket.

Download or read book Structure and Dynamics of Water and Aqueous Solutions written by and published by . This book was released on 1984 with total page 292 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Molecular Dynamics Simulation of Liquid Water written by and published by . This book was released on 2005 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt: The structure, dynamical and electronic properties of liquid water utilizing different hybrid density functionals were tested within the plane wave framework of first principles molecular dynamics simulations. The computational approach, which employs modified functionals with short-ranged Hartree-Fock exchange, was first tested in calculations of the structural and bonding properties of the water dimer and cyclic water trimer. Liquid water simulations were performed at the state point of 350 K at the experimental density. Simulations included three different hybrid functionals, a meta functional, four gradient corrected functionals, the local density and Hartree-Fock approximation. It is found that hybrid functionals are superior in reproducing the experimental structure and dynamical properties as measured by the radial distribution function and self diffusion constant when compared to the pure density functionals. The local density and Hartree-Fock approximations show strongly over- and under-structured liquids, respectively. Hydrogen bond analysis shows that the hybrid functionals give slightly smaller averaged numbers of hydrogen bonds and similar hydrogen bond populations as pure density functionals. The average molecular dipole moments in the liquid from the three hybrid functionals are lower than from the corresponding pure density functionals.

Download or read book Structure of Water and Aqueous Solutions written by Werner A. P. Luck and published by . This book was released on 1974 with total page 628 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Molecular Basics of Liquids and Liquid Based Materials written by Katsura Nishiyama and published by Springer Nature. This book was released on 2022-01-03 with total page 469 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book sheds light on the molecular aspects of liquids and liquid-based materials such as organic or inorganic liquids, ionic liquids, proteins, biomaterials, and soft materials including gels. The reader discovers how the molecular basics of such systems are connected with their properties, dynamics, and functions. Once the use and application of liquids and liquid-based materials are understood, the book becomes a source of the latest, detailed knowledge of their structures, dynamics, and functions emerging from molecularity. The systems discussed in the book have structural dimensions varying from nanometers to millimeters, thus the precise estimation of structures and dynamics from experimental, theoretical, and simulation methods is of crucial importance. Outlines of the practical knowledge needed in research and development are helpfully included in the book.

Download or read book Time Dependent Properties of Liquid Water written by and published by . This book was released on 2005 with total page 31 pages. Available in PDF, EPUB and Kindle. Book excerpt: A series of 30 ps first principles molecular dynamics simulations in the microcanonical ensemble were carried out to investigate transport and vibrational properties of liquid water. To allow for sufficient sampling, the thermodynamic constraints were set to an elevated temperature of around 423 K and a density of 0.71 g/cm3 corresponding to the saturated liquid density for the Becke-Lee-Yang-Parr (BLYP) representation of water. Four simulations using the Car-Parrinello molecular dynamics (CPMD) technique with varying values of the fictitious electronic mass ([mu]) and two simulations using the Born-Oppenheimer molecular dynamics (BOMD) technique are analyzed to yield structural and dynamical information. At the selected state point, the simulations are found to exhibit non-glassy dynamics and yield consistent results for the liquid structure and the self-diffusion coefficient, although the statistical uncertainties in the latter quantity are quite large. Consequently, it can be said that the CPMD and BOMD methods produce equivalent results for these properties on the time scales reported here. However, it was found that the choice of [mu] affects the frequency spectrum of the intramolecular modes, shifting them slightly to regions of lower frequency. Using a value of [mu] = 400 a.u. results in a significant drift in the electronic kinetic energy of the system over the course of 30 ps and a downward drift in the ionic temperature. Therefore, for long trajectories at elevated temperatures, lower values of this parameter are recommended for CPMD simulations of water.

Download or read book Ions in Water and Biophysical Implications written by Yizhak Marcus and published by Springer Science & Business Media. This book was released on 2012-08-13 with total page 224 pages. Available in PDF, EPUB and Kindle. Book excerpt: Over the past decade, numerous books have attempted to explain ions in aqueous solutions in relation to biophysical phenomena. Ions in Water and Biophysical Implications, from Chaos to Cosmos offers a physicochemical point of view of the spread of this matter and suggests innovative solutions that will challenge the biophysics research establishment. Starting with a throughout discussion of the properties of liquid water, in particular as a structured liquid with an extensive hydrogen bonded structure, the book examines water as a solvent for gases, non-electrolytes, and electrolytes and reviews the properties, sizes and thermodynamics of isolated and aqueous ions, as well as their interactions, including those of polyelectrolytes. The effects of ions on water structure, including those on solvent dynamics and certain thermodynamic quantities, are presented. This volume investigates water surfaces with its vapour, with another liquid, and with a solid, as well as the effects of solutes, including simple ions and the water-miscible non-electrolytes. Surfaces are relevant to biomolecular and colloidal systems and the book discusses briefly surfactants, micelles and vesicles. Finally, the book concludes with a review of the various biophysical implications involving chaotropic and kosmotropic ions in homogeneous solutions and the Hofmeister series for ions concerning biomolecular and colloidal systems and some aspects of protein hydration and K+/Na+ selectivity in ion channels. Ions in Water and Biophysical Implications, from Chaos to Cosmos will appeal to physical chemists, biophysicists, biochemists, as well as to all students and researchers involved in the study of aqueous solutions.

Download or read book Water in Biological and Chemical Processes written by Biman Bagchi and published by Cambridge University Press. This book was released on 2013-11-14 with total page 383 pages. Available in PDF, EPUB and Kindle. Book excerpt: A unified overview of the dynamical properties of water and its unique and diverse role in biological and chemical processes.

Download or read book Encyclopedia of Interfacial Chemistry written by and published by Elsevier. This book was released on 2018-03-29 with total page 5276 pages. Available in PDF, EPUB and Kindle. Book excerpt: Encyclopedia of Interfacial Chemistry: Surface Science and Electrochemistry, Seven Volume Set summarizes current, fundamental knowledge of interfacial chemistry, bringing readers the latest developments in the field. As the chemical and physical properties and processes at solid and liquid interfaces are the scientific basis of so many technologies which enhance our lives and create new opportunities, its important to highlight how these technologies enable the design and optimization of functional materials for heterogeneous and electro-catalysts in food production, pollution control, energy conversion and storage, medical applications requiring biocompatibility, drug delivery, and more. This book provides an interdisciplinary view that lies at the intersection of these fields. Presents fundamental knowledge of interfacial chemistry, surface science and electrochemistry and provides cutting-edge research from academics and practitioners across various fields and global regions