Computer simulation studies of the structure and dynamics of ions and non–polar solutes in water

The origins of electronic spectral broadening in solutions, glasses and proteins are discussed via three pulse stimulated echo peak–shift measurements. Spectral densities for dye molecules in polar solutions are presented and discussed in terms of molecular models for the dynamics. The breakdown of the harmonic bath picture at low frequencies is presented. Finally, echo measurements on light harvesting complexes of purple bacteria are presented and it is shown that the energy transfer timescale can be obtained from peak–shift measurements.

As quantum chemistry plays a more and more central role in many complicated chemical problems, it has become necessary to obtain accurate results for large molecular systems. Conventional quantum chemistry methods are either too expensive to apply to large systems or too approximate for the results to be reliable, and they fail to satisfy this requirement. A variety of different approaches is being developed with the aim of achieving this goal: local correlation methods; divide-and-conquer methods; linear-scaling density functional methods based on the fast multipole and other approximations; effective potential methods; and hybrid methods. ONIOM (our N-layered integrated molecular orbital plus molecular mechanics method), developed by the authors, is a hybrid method in which a large molecular system is divided into onion-skin-like layers, and different quantum chemistry/molecular mechanics methods are used for different parts of the system; the results are combined to extrapolatively estimate the results of high-level calculation for the real system. Several applications of ONIOM will be discussed.

Research Highlights

A Comprehensive Treatise on Inorganic and Theoretical Chemistry

International Journal of Modern Physics BVol. 06, No. 23n24, pp. 3687-3693 (1992) I. CLUSTERS: Formation, Structure and Phase TransitionsNo AccessAB INITIO ELECTRONIC STRUCTURE CALCULATIONS ON DODECAHEDRAL CLUSTERS OF TWENTY WATER MOLECULES AND THEIR GAS-PHASE CLATHRATES WITH ALKALI METAL CATIONSJ. Cioslowski and A. NanayakkaraJ. CioslowskiDepartment of Chemistry and Supercomputer Computations Research Institute, Florida State University, Tallahassee, Florida 32306–3006, USA and A. NanayakkaraDepartment of Chemistry and Supercomputer Computations Research Institute, Florida State University, Tallahassee, Florida 32306–3006, USAhttps://doi.org/10.1142/S0217979292001754Cited by:10 PreviousNext AboutSectionsPDF/EPUB ToolsAdd to favoritesDownload CitationsTrack CitationsRecommend to Library ShareShare onFacebookTwitterLinked InRedditEmail You currently do not have access to the full text article. Recommend the journal to your library today! FiguresReferencesRelatedDetailsCited By 10Hydrated Alkali Metal Ions: Spectroscopic Evidence for ClathratesRichard J. Cooper, Terrence M. Chang and Evan R. Williams10 July 2013 | The Journal of Physical Chemistry A, Vol. 117, No. 30Interaction between OH Radical and the Water InterfaceShiyu Du and Joseph S. Francisco3 May 2008 | The Journal of Physical Chemistry A, Vol. 112, No. 21Theoretical studies of Na(H2O)19–21+ and K(H2O)19–21+ clusters: explaining the absence of magic peak for Na(H2O)20+Arshad Khan1 Apr 2004 | Chemical Physics Letters, Vol. 388, No. 4-6On the interactions between atmospheric radicals and cloud droplets: A molecular picture of the interfaceQicun Shi, Stephen D. Belair, Joseph S. Francisco and Sabre Kais6 August 2003 | Proceedings of the National Academy of Sciences, Vol. 100, No. 17The effect of ions on solid–liquid phase transition in small water clusters. A molecular dynamics simulation studyAndrei V. Egorov, Elena N. Brodskaya and Aatto Laaksonen8 Apr 2003 | The Journal of Chemical Physics, Vol. 118, No. 14Complexation of Li+, Na+, and K+ by water and ammoniaK Laidig1 Feb 2000 | Coordination Chemistry Reviews, Vol. 197, No. 1Dynamics of a Highly Charged Ion in Aqueous Solutions: MD Simulations of Dilute CrCl 3 Aqueous Solutions Using Interaction Potentials Based on the Hydrated Ion ConceptJosé M. Martínez, Rafael R. Pappalardo, Enrique Sánchez Marcos, Keith Refson and Sofía Díaz-Moreno et al.2 April 1998 | The Journal of Physical Chemistry B, Vol. 102, No. 17Theoretical studies of structures and stabilization energies of (H2O)26, (H2O)27 and (H2O)28 pentakaidecahedral clustersArshad Khan1 Aug 1996 | Chemical Physics Letters, Vol. 258, No. 5-6Theoretical studies of tetrakaidecahedral structures of (H2O)24, (H2O)25 and (H2O)26 clustersArshad Khan1 May 1996 | Chemical Physics Letters, Vol. 253, No. 3-4Quantum-Mechanical investigation of large water clustersKarl N. Kirschner and George C. Shields12 Feb 1994 | International Journal of Quantum Chemistry, Vol. 52, No. S28 Recommended Vol. 06, No. 23n24 Metrics History PDF download

The virial stress is the most commonly used definition of stress in discrete particle systems. This quantity includes two parts. The first part depends on the mass and velocity (or, in some versions, the fluctuation part of the velocity) of atomic particles, reflecting an assertion that mass transfer causes mechanical stress to be applied on stationary spatial surfaces external to an atomic‐particle system. The second part depends on interatomic forces and atomic positions, providing a continuum measure for the internal mechanical interactions between particles. Historic derivations of the virial stress include generalization from the virial theorem of Clausius (1870) for gas pressure and solution of the spatial equation of balance of momentum. The virial stress is stress‐like a measure for momentum change in space. This paper shows that, contrary to the generally accepted view, the virial stress is not a measure for mechanical force between material points and cannot be regarded as a measure for mechanical stress in any sense. The lack of physical significance is both at the individual atom level in a time‐resolved sense and at the system level in a statistical sense. It is demonstrated that the interatomic force term alone is a valid stress measure and can be identified with the Cauchy stress. The proof in this paper consists of two parts. First, for the simple conditions of rigid translation, uniform tension and tension with thermal oscillations, the virial stress yields clearly erroneous interpretations of stress. Second, the conceptual flaw in the generalization from the virial theorem for gas pressure to stress and the confusion over spatial and material equations of balance of momentum in theoretical derivations of the virial stress that led to its erroneous acceptance as the Cauchy stress are pointed out. Interpretation of the virial stress as a measure for mechanical force violates balance of momentum and is inconsistent with the basic definition of stress. The versions of the virial‐stress formula that involve total particle velocity and the thermal fluctuation part of the velocity are demonstrated to be measures of spatial momentum flow relative to, respectively, a fixed reference frame and a moving frame with a velocity equal to the part of particle velocity not included in the virial formula. To further illustrate the irrelevance of mass transfer to the evaluation of stress, an equivalent continuum (EC) for dynamically deforming atomistic particle systems is defined. The equivalence of the continuum to discrete atomic systems includes (i) preservation of linear and angular momenta, (ii) conservation of internal, external and inertial work rates, and (iii) conservation of mass. This equivalence allows fields of work‐ and momentum‐preserving Cauchy stress, surface traction, body force and deformation to be determined. The resulting stress field depends only on interatomic forces, providing an independent proof that as a measure for internal material interaction stress is independent of kinetic energy or mass transfer.

Surface Review and LettersVol. 04, No. 04, pp. 757-770 (1997) ReviewsNo AccessADSORPTION OF WATER ON NaClGEORGE E. EWING and STEVEN J. PETERSGEORGE E. EWINGDepartment of Chemistry, Indiana University, Bloomington, IN 47405, USA and STEVEN J. PETERSDepartment of Chemistry, Indiana University, Bloomington, IN 47405, USAhttps://doi.org/10.1142/S0218625X97000742Cited by:17 PreviousNext AboutSectionsPDF/EPUB ToolsAdd to favoritesDownload CitationsTrack CitationsRecommend to Library ShareShare onFacebookTwitterLinked InRedditEmail FiguresReferencesRelatedDetailsCited By 17Nanoparticle-assisted acceleration of laser-irradiated low-density He ionsEva Klimešová, Olena Kulyk, Laura Dittrich, Jakob Andreasson and Maria Krikunova27 December 2021 | Physical Review A, Vol. 104, No. 6Adsorption Capacities of Hygroscopic Materials Based on NaCl-TiO 2 and NaCl-SiO 2 Core/Shell ParticlesMarie Bermeo, Nabil El Hadri, Florent Ravaux, Abdelali Zaki and Linda Zou et al.13 Feb 2020 | Journal of Nanotechnology, Vol. 2020Influence of stearic acid coating of the NaCl surface on the reactivity with NO 2 under humidityS. Sobanska, J. Barbillat, M. Moreau, N. Nuns and I. De Waele et al.1 January 2015 | Physical Chemistry Chemical Physics, Vol. 17, No. 16Impacts of Surface Adsorbed Catechol on Tropospheric Aerosol Surrogates: Heterogeneous Ozonolysis and Its Effects on Water UptakeLaurie A. Woodill, Erinn M. O’Neill and Ryan Z. Hinrichs1 July 2013 | The Journal of Physical Chemistry A, Vol. 117, No. 27Interfacial Dushman-like Chemistry in Hydrated KIO 3 Layers Grown on KIMatthew A. Brown, Paul D. Ashby, Maria J. Krisch, Zhi Liu and B. Simon Mun et al.29 July 2010 | The Journal of Physical Chemistry C, Vol. 114, No. 33A critical assessment of theoretical methods for finding reaction pathways and transition states of surface processesJiří Klimeš, David R Bowler and Angelos Michaelides3 February 2010 | Journal of Physics: Condensed Matter, Vol. 22, No. 7Bromine Enrichment in the Near-Surface Region of Br-Doped NaCl Single Crystals Diagnosed by Rutherford Backscattering SpectrometryM. Hess, U. K. Krieger, C. Marcolli, T. Huthwelker and M. Ammann et al.27 April 2007 | The Journal of Physical Chemistry A, Vol. 111, No. 20Influence of multiple reflections on transmission through a stack of platesW. L. Schaich, George E. Ewing and Robert L. Karlinsey20 September 2006 | Applied Optics, Vol. 45, No. 27Surface Adsorbed Water on NaCl and Its Effect on Nitric Acid Reactivity with NaCl PowdersSutapa Ghosal and John C. Hemminger24 August 2004 | The Journal of Physical Chemistry B, Vol. 108, No. 37Thin Film Water on Insulator SurfacesGeorge E. Ewing, Michelle Foster, Will Cantrell and Vlad Sadtchenko1 Jan 2003Adsorption of water on the NaCl(001) surface. II. An infrared study at ambient temperaturesMichelle C. Foster and George E. Ewing15 Apr 2000 | The Journal of Chemical Physics, Vol. 112, No. 15Water content and morphology of sodium chloride aerosol particlesDavid D. Weis and George E. Ewing1 September 1999 | Journal of Geophysical Research: Atmospheres, Vol. 104, No. D17Water adsorption by hydrophobic organic surfaces: Experimental evidence and implications to the atmospheric properties of organic aerosolsElan Thomas, Yinon Rudich, Sofia Trakhtenberg and Rachel Ussyshkin1 July 1999 | Journal of Geophysical Research: Atmospheres, Vol. 104, No. D13The Reaction of Nitrogen Dioxide with Sea Salt AerosolDavid D. Weis and George E. Ewing9 June 1999 | The Journal of Physical Chemistry A, Vol. 103, No. 25Effect of Water on the HNO 3 Pressure Dependence of the Reaction between Gas-Phase HNO 3 and NaCl SurfacesSutapa Ghosal and John C. Hemminger9 June 1999 | The Journal of Physical Chemistry A, Vol. 103, No. 25Measurements of the H 2 SO 4 mass accommodation coefficient onto polydisperse aerosolA. Jefferson, F. L. Eisele, P. J. Ziemann, R. J. Weber and J. J. Marti et al.1 August 1997 | Journal of Geophysical Research: Atmospheres, Vol. 102, No. D15H2O on NaCl: From Single Molecule, to Clusters, to Monolayer, to Thin Film, to DeliquescenceGeorge E. Ewing Recommended Vol. 04, No. 04 Metrics Downloaded 18 times History Received 14 November 1996 PDF download

Use of UV methods for measurement of protein and nucleic acid concentrations.

Theoretical Study of the Formation Methane in the Reaction of Methyl Radical with Propanol-2

Theoretical Study on Reaction Pathways of Methyl Radical with Ethylamine

Block copolymers dissolved in a selective solvent form micelles that can be regarded as model colloidal dispersions because by tailoring the copolymer composition, the relative size of core and corona can be controlled. This enables the interaction potential to be varied, such that either hard or soft sphere ordering can be observed above the liquid–solid (sol–gel) transition. Here we review recent work on the structure and rheology of micellar phases formed by block copolymers in solution. First, the structure of solid and liquid micellar phases is considered, and its relationship to flow properties of gels and sols is discussed. Then the ordering of hard versus soft spheres is considered in the context of experimental phase diagrams for poly(styrene)–poly(isoprene) in decane and poly(oxyethylene)–poly(oxybutylene) diblock copolymers in water. The use of experiments in the linear viscoelastic regime to locate the gelation (liquid–solid) transition is then reviewed, and the application of measurements in the linear viscoelastic regime to study relaxation phenomena is also outlined. The nonlinear flow behaviour of micellar block copolymer solutions is then considered. In particular the focus is on the development of a yield stress in the solid phase, creep and stress relaxation measurements which throw light on flow mechanisms, and Fourier transform rheology which provides a quantitative measure of nonlinear viscoelasticity under oscillatory shear. Finally, an overview is provided of recent small–angle scattering experiments that have probed the mechanisms of macroscopic alignment of body–centred and face–centred cubic micellar phases subjected to large–amplitude oscillatory shear or steady shear in a Couette cell.

The PVTx properties of aqueous electrolyte solutions containing Li+, Na+, K+, Mg2+, Ca2+, Cl− and SO42− under conditions of CO2 capture and sequestration

The Geometries and Stabilities of Neutral and Anionic Vanadium Doped Germanium Clusters VGen0/-( n = 9 - 13): Density Functional Theory Investigations

The Italian National Project of Astrobiology-Life in Space-Origin, Presence, Persistence of Life in Space, from Molecules to Extremophiles.

The remarkable stability of water–in–crude oil emulsions is due to the presence of a complex adsorbed layer at the surfaces of the dispersed droplets. Except for its role as a steric barrier, little is known about the in situ properties of this interfacial structure. In this study, new insights into the adsorbed layer are provided by direct micrometre–scale measurements. At low crude content in the bulk where, according to interfacial tension isotherms, there should be little or no surfactants on the droplet surface, the adsorbed layer displays pronounced rigidity and is capable of preventing coalescence and coagulation of the droplets. Such interfaces are highly dissipative and can be well described by the Boussinesq–Scriven model. As the supply of surface active materials in the bulk (i.e. the crude content) increases , the adsorbed layer transforms from a rigid structure to a fluid interface. This fluid layer continues to inhibit coalescence, although signs of weak interdroplet adhesion begin to appear. Under area compression, the fluid interface will discharge micrometre–sized emulsion droplets into the oil phase via a ‘budding’ mechanism.