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3D map of molecular density in water
Understanding the condensed states of matter at the microscopic levelis one of the fundamental problems in physics and chemistry. Until veryrecently our understanding of the local structures in liquids and amorphoussolids has relied largely upon the radial distribution functions of atoms.In my work the microstructures in liquids and amorphous solids are studiedwith the aid of the spatial distribution functions which enable the detailedunambiguous elucidation of atomic 3D coordination. I have now extendedthis recent methodology to the studies of the time-dependent phenomena(such as the local density fluctuations in any spatial direction). My computersimulations focus mainly on hydrogen-bonded systems, such as water andalcohols, nonelectrolyte solutions, amorphous ices, etc. These theoreticalstudies of 3D coordination structures are supported by experimental neutronand X-ray investigations (collaboration with A.Soper, ISIS Facility, RutherfordLaboratory, UK).
Another area of research concerns the development of simple polarizablemodels for molecules that explicitly incorporate results from ab-initioquantum-chemical studies. One such model for water, the polarizablepoint-charge (PPC) potential, is known to describe very accurately boththe liquid and the gas states. This PPC potential can be particularly usefulin the studies involving metastable, supercritical and interfacial water.Nonequilibrium simulation techniques are employed to probe the microscopicdynamics in liquids, particularly those related to dielectric responseand ion transport (collaboration with P.Kusalik, Dalhousie University,Canada).
Quartz-like form of ice
In many aqueous environments water molecules interact with local electricfields (generated by the surface of a solid particle or by a large biomolecule)which modify the physical-chemical properties of water. Molecular dynamicssimulation technique can be used to investigate these electric field effectson the properties and phase transitions of water. For many years waterhas been known to exist in several reasonably well-understood crystallinemodifications of ice. Our computer simulations indicate that the applicationof an electric field to a supercooled liquid water under pressure of 3-5kbar produces a previously unobserved low-density form of ice with a uniquequartz-like structure.
Atmospheric water vapor plays an important role in the radiative balanceof the Earth. Water molecules can absorb both the short-wavelength solarradiation arriving in the atmosphere and the outgoing infrared (IR) surfaceradiation. We argue that an additional "greenhouse" trappingof the long-wavelength IR radiation may result from an interaction of watervapor with major atmospheric gases, such as oxygen and nitrogen. Infraredspectra for H2O-O2 and H2O-N2 complexes exhibit several interaction-inducedlow-frequency modes, while their estimated atmospheric fractions appearto be larger than for many recognized "greenhouse" species. Thisimplies that atmospheric H2O-O2 and H2O-N2 complexes may absorb more ofthe Earth's surface radiation than individual molecules and thus contributeto a "greenhouse" effect.
SCWO Process
A miniature flow reactor is employed in experimental supercritical wateroxidation (SCWO) studies. This project is aimed at the development of theenvironmental technology for rapid and safe destruction of hazardous organicmaterials, such as PCBs, dioxins, solvents, pesticides, etc. Test runsare conducted to investigate the SCWO process conditions for various organics,the corrosion of reactor components and the oxidizer (H2O2) chemistry.
The interest in water near and above its critical point has grown dramaticallyover recent years due to increased applications of high-temperature aqueousfluids in technologically important areas. The International Associationfor the Properties of Water and Steam (IAPWS) established a Task Group(TG) on Computer Simulation to facilitate practical use of molecular-basedcomputer simulations of water and aqueous fluids that are relevant to powercycles and other industrial application. As the Chair of this Task GroupI coordinate the preparation of internationally agreed-upon, criticallyevaluated representations of thermophysical property data for computersimulated water and aqueous fluids for use by scientists and engineers.
Svishchev I.M. and Zassetsky A.Yu. "Self-Diffusion Process in Water:Spatial Picture of Single-Particle Density Fluctuations" J.Chem.Phys.,113, 7432-7436 (2000).
Svishchev I.M. and Zassetsky A.Yu. "Three-dimensional Picture ofDynamical Structure in Liquid Water" J.Chem.Phys., 112,1367-1372 (2000).
Svishchev I.M., Zassetsky A.Yu. and Kusalik P.G. "Solvation Structuresin 3D" Chem.Phys., 258, 181-189 (2000).
Kusalik P.G., Laaksonen A. and Svishchev I.M. "Spatial Structurein Molecular Liquids", In Molecular Dynamics: from classical toquantum methods, Eds. P.B. Balbuena and J.M. Seminario, Elsevier, NewYork, 1999, 36 pp (book chapter).
Svishchev I.M. and Kusalik P.G. "Method for Enhanced Sampling inSimulations of Dynamical Systems" Phys.Rev.E, 59, 3753-3755(1999).
Svishchev I.M. and Hayward T.M. "Phase Coexistence Properties forthe Polarizable Point Charge Model of Water and the Effects of AppliedElectric Field" J.Chem.Phys., 101, 9034-9038 (1999).
Svishchev I.M. and Boyd R.J. "Van der Waals Complexes of Waterwith Oxygen and Nitrogen: Infrared Spectra and Atmospheric Implications"J.Phys.Chem.A, 102, 7294-7397 (1998).
Murashov V. V. and Svishchev I.M. "Quartz Family of Silica Structures:A Comparative Study of Quartz, Moganite and Orthorhombic Silica, and TheirPhase Transformations" Phys.Rev.B, 57, 5639-5649 (1998).
Laaksonen A., Kusalik P.G. and Svishchev I.M. "Three-dimensionalStructure in Water-Methanol Mixtures" J.Phys.Chem., 101,5910-5918 (1997).
Svishchev I.M., Murashov V. and Kusalik P.G. "Orthorhombic Quartz-likePolymorph of Silica" Phys.Rev.B., 55, 561-567 (1997).
Svishchev I.M. and Kusalik P.G. "Quartz-like Polymorph of Ice"Phys.Rev.B, 53, 8815-8819 (1996).
Svishchev I.M., Kusalik P.G., Wang J. and Boyd R.J. "PolarizablePoint Charge Model for Water: Results under Normal and Extreme Conditions"J.Chem.Phys., 105, 4742-4750 (1996).
Svishchev I.M. and Kusalik P.G. "Electrofreezing of Liquid Water:A Microscopic Perspective" J.Am.Chem.Soc., 118, 649-654(1996).
Svishchev I.M. and Kusalik P.G. "Crystallization of Molecular Liquidsin Computer Simulations: Carbon Dioxide" Phys.Rev.Lett., 75,3289-3292 (1995).
Kusalik P.G., Linden F. and Svishchev I.M. "Calculation of theThird Virial Coefficient for Water" J.Chem.Phys., 103,10169-10177 (1995).
Kusalik P.G. and Svishchev I.M. "The Spatial Structure in LiquidWater" Science, 265, 1219-1221 (1994).
Svishchev I.M. and Kusalik P.G. "Structure in Liquid Methanol fromSpatial Distribution Functions" J.Chem.Phys., 100, 5165-5171(1994).
Svishchev I.M. and Kusalik P.G. "Crystallization of Liquid Waterin a Molecular Dynamics Simulation" Phys.Rev.Lett., 73,975-978 (1994).
| Last updated: December 10, 2000 Maintained by Igor Svishchev, Chemistry Dpt., Trent University. |  |  |
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