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Articles 5101 - 5130 of 7341

Full-Text Articles in Physical Sciences and Mathematics

Harmonic Gauge In Canonical Gravity, K. V. Kuchal, Charles G. Torre Jan 1991

Harmonic Gauge In Canonical Gravity, K. V. Kuchal, Charles G. Torre

All Physics Faculty Publications

The Isham-Kuchař representation theory of the spacetime diffeomorphism group in canonical geometrodynamics is implemented in the context of harmonic coordinate conditions. The representation is carried by either an extended phase space, consisting of the cotangent bundle over the space of three-metrics, spacelike embeddings, and Lagrange multipliers which serve to enforce the harmonic gauge in the action, or by a reduced space in which the multipliers are eliminated. The approach used here is applicable to any generally covariant theory and to any coordinate conditions. The physical interpretation of the diffeomorphism Hamiltonians is discussed and compared with the analogous interpretation given by …

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Exact And Asymptotic Scaling Solutions For Fragmentation With Mass Loss, M. Cai, Boyd F. Edwards, H. Han Jan 1991

Exact And Asymptotic Scaling Solutions For Fragmentation With Mass Loss, M. Cai, Boyd F. Edwards, H. Han

All Physics Faculty Publications

Exact and asymptotic solutions to a linear rate equation for fragmentation with mass loss are presented. Solutions for spatially discrete random bond annihilation illustrate the mutual exclusiveness of the fragmentation and recession terms in the rate equation. Exact solutions for deterministic equal fragment recession show that continuous mass loss between fragmentation events can be approximated by discrete mass loss during fragmentation events when this mass loss is small. Evidence that continuous and discrete mass loss preclude shattering mass loss, the loss of mass to zero-mass particles due to runaway fragmentation, is presented. General asymptotic scaling forms, general solutions reflecting arbitrary …

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Restoration And Expansion Of Bear River Migratory Bird Refuge, Brigham City, Utah, Environmental Assessment, U.S. Fish And Wildlife Service Jan 1991

Restoration And Expansion Of Bear River Migratory Bird Refuge, Brigham City, Utah, Environmental Assessment, U.S. Fish And Wildlife Service

Environmental Assessments (UT)

This Environmental Assessment is designed to evaluate possible actions for preserving and managing the wetland habitat on Bear River Migratory Bird Refuge (Refuge) and to consider additional wetlands for protection of environmental, wildlife, and recreational values.

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Rainbow Bridge National Monument General Management Plan, Development Concept Plan, Resource Management Plan, Interpretive Prospectus, And Environmental Assessment, United States, Department Of The Interior, National Park Service Jan 1991

Rainbow Bridge National Monument General Management Plan, Development Concept Plan, Resource Management Plan, Interpretive Prospectus, And Environmental Assessment, United States, Department Of The Interior, National Park Service

Resource Management Plans (UT)

This General Management Plan provides the National Park Service with direction for long-range management, development, and use of the Rainbow Bridge National Monument. The plan responds to new issues identified during the planning process when the draft plan was published in September of 1990. A main concern expressed during public review of the draft plan was diverse public expectations for visitor experience, crowding, and the high number of visitors accessing a limited area of Rainbow Bridge. In addition, the plan and environmental assessment address these diverse public expectations along with the issues of a visitor experience, protection of natural and …

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Silicon (2p) Surface Core-Level Line Shape Of Si(111)—B, J. E. Rowe, G. K. Wertheim, D. Mark Riffe Jan 1991

Silicon (2p) Surface Core-Level Line Shape Of Si(111)—B, J. E. Rowe, G. K. Wertheim, D. Mark Riffe

All Physics Faculty Publications

Several recent structural studies of the Si(111)–B ((3)1/2×(3)1/2) surface have established that the boron atoms occupy substitutional sites in the second full Si layer and have Si adatoms directly above them. High‐resolution (∼80–100 meV) Si(2p) core‐level photoemission was used to determine the B‐induced perturbation of the surface Si atoms. The samples were prepared by surface segregation from Si(111) wafers (∼1.5 at. % B) after thermally removing the thin protective oxide layer on the surface. Photoemission spectra for photon energies from 110 to 140 eV show three peaks, indicative of at least two well‐separated spin‐orbit …

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A Deformation Theory Of Self-Dual Einstein Spaces, Charles G. Torre Jan 1991

A Deformation Theory Of Self-Dual Einstein Spaces, Charles G. Torre

All Physics Faculty Publications

The self-dual Einstein equations on a compact Riemannian 4-manifold can be expressed as a quadratic condition on the curvature of an $SU(2)$ (spin) connection which is a covariant generalization of the self-dual Yang-Mills equations. Local properties of the moduli space of self-dual Einstein connections are described in the context of an elliptic complex which arises in the linearization of the quadratic equations on the $SU(2)$ curvature. In particular, it is shown that the moduli space is discrete when the cosmological constant is positive; when the cosmological constant is negative the moduli space can be a manifold the dimension of which …

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Gaussian Reference Fluid And Interpretation Of Quantum Geometrodynamics, Karel Kucha, Charles G. Torre Jan 1991

Gaussian Reference Fluid And Interpretation Of Quantum Geometrodynamics, Karel Kucha, Charles G. Torre

All Physics Faculty Publications

The Wheeler-DeWitt equation of vacuum geometrodynamics is turned into a Schrödinger equation by imposing the normal Gaussian coordinate conditions with Lagrange multipliers and then restoring the coordinate invariance of the action by parametrization. This procedure corresponds to coupling the gravitational field to a reference fluid. The source appearing in the Einstein law of gravitation has the structure of a heat-conducting dust. When one imposes only the Gaussian time condition but not the Gaussian frame conditions, the heat flow vanishes and the dust becomes incoherent. The canonical description of the fluid uses the Gaussian coordinates and their conjugate momenta as the …

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Ionospheric Physics, Jan Josef Sojka Jan 1991

Ionospheric Physics, Jan Josef Sojka

All Physics Faculty Publications

The author has taken a parochial view of the subject matter
under the title of ionospheric physics. Physics is used as the
key to separating this section of the aeronomy review from the
other aeronomy reports. Specifically, work categorized as
chemistry, optical emissions, and thermosphere will not be
reviewed in this section. However, coupling to the
thermosphere and more specifically to the magnetosphere is
considered. A brief section is also included on active
experiments which is a productive area in plasma physics and
also to some extent in ionospheric physics, but one that has
fallen on hard times with regard …

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Field-Aligned Current Associated With A Distorted Two-Cell Convection Pattern During Northward Interplanetary Magnetic Field, Lie Zhu, Robert W. Schunk, Jan Josef Sojka Jan 1991

Field-Aligned Current Associated With A Distorted Two-Cell Convection Pattern During Northward Interplanetary Magnetic Field, Lie Zhu, Robert W. Schunk, Jan Josef Sojka

All Physics Faculty Publications

A systematic study of the influence of the ionospheric conductance on the field-aligned current associated with a distorted two-cell convection pattern during northward interplanetary magnetic field (IMF) has been conducted. Our modeling results indicate that the NBZ current can be associated with the distorted two-cell convection for most of the ionospheric conductivity conditions. It is shown that the conductivity conditions related to the seasonal variation and the aurora activity can significantly influence the basic features of the field-aligned current associated with a distorted two-cell convection pattern. It is found that the increase of the field-aligned current in the polar cap …

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Revised Global Model Of Thermosphere Winds Using Satellite And Ground-Based Observations, A E. Hedin, M A. Biondi, R G. Burnside, G Hernandez, R M. Johnson, T L. Killeen, C Mazaudier, J W. Meriwether, J E. Salah, R W. Smith, N W. Spencer, Vincent B. Wickwar, T S. Virdi Jan 1991

Revised Global Model Of Thermosphere Winds Using Satellite And Ground-Based Observations, A E. Hedin, M A. Biondi, R G. Burnside, G Hernandez, R M. Johnson, T L. Killeen, C Mazaudier, J W. Meriwether, J E. Salah, R W. Smith, N W. Spencer, Vincent B. Wickwar, T S. Virdi

All Physics Faculty Publications

Thermospheric wind data obtained from the Atmosphere Explorer E and Dynamics Explorer 2 satellites have been combined with wind data for the lower and upper thermosphere from ground-based incoherent scatter radar and Fabry-Perot optical interferometers to generate a revision (HWM90) of the HWM87 empirical model and extend its applicability to 100 km. Comparison of the various data sets with the aid of the model shows in general remarkable agreement, particularly at mid and low latitudes. The ground-based data allow modeling of seasonal/diurnal variations, which are most distinct at mid latitudes. While solar activity variations are now included, they are found …

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Calibration Of A Parametric-Stochastic Model, Zhida Song, L. Douglas James Jan 1991

Calibration Of A Parametric-Stochastic Model, Zhida Song, L. Douglas James

Reports

Conceptually, stochastic parametric modeling offers a powerful tool to select a scale for expressing catchment variability for hydrologic simulation and relating model parameters to catchment characteristics. Practically, success depends on having an efficient method for model calibration. The calibration of a stochastic model is much more difficult than a deterministic one because simulation shifts from using fixed parameters to simulate of flows as deterministic values to taking multiple combinations of paramter values randomly from distributions to simulate flows as stochastic variables. The proposed method calibrates the first two moments of each parameter distribution to represent the average and the variability …

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Studies Related To Nutrients Entering Groundwater From The Heber Valley Sewer Farm And Dairies, Roland W. Jeppson, Joan Mclean, Calvin G. Clyde, Scott Korom Jan 1991

Studies Related To Nutrients Entering Groundwater From The Heber Valley Sewer Farm And Dairies, Roland W. Jeppson, Joan Mclean, Calvin G. Clyde, Scott Korom

Reports

Foreword: This report includes the results from a two year study in the Heber Valley to determine amounts of nutrients that are entering the groundwaters of the Heber Valley, and might ultimately enter Deer Creek Reservoir. Since Deer Creek Reservoir in Heber Valley, Utah supplies approximately 65 percent of the water distributed to Salt Lake County, the maintenance of its quality is of considerable importance. To maintain the quality of this reservoir and limit its eutrophication "best management" practices for surface water have been implemented gradually during the past decade in Heber Valley. These practices have significantly improved the qualities …

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Constraints On Unroofing Rates In The High Himalaya, Eastern Nepal, Mary S. Hubbard, L. H. Royden, K. V. Hodges Jan 1991

Constraints On Unroofing Rates In The High Himalaya, Eastern Nepal, Mary S. Hubbard, L. H. Royden, K. V. Hodges

Geosciences Faculty Publications

Thermobarometric data for samples across the Main Central thrust zone in eastern Nepal show an inversion in temperature but not in pressure. These data have been interpreted to represent a portion of the paleogeotherm at the time of Main Central thrust deformation. A 40Ar/39Ar age on hornblende (closure temperature (Tc)=500±50°C) constrains the timing of this deformation to be ∼21±0.2 Ma. The 40Ar/39Ar ages of other minerals (muscovite, Tc=350°C, age (t)=12.0±0.2 Ma; K-feldspar, Tc=220°C, t=8.0±0.2 Ma) from the same location further constrain the cooling history of this region. Together the geochronologic and thermobarometric data yield an average unroofing rate of 1.2±0.6 …

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Hydrogeology Of Thrust Faults And Crystalline Thrust Sheets: Results Of Combined Field And Modeling Studies, Craig B. Forster, James P. Evans Jan 1991

Hydrogeology Of Thrust Faults And Crystalline Thrust Sheets: Results Of Combined Field And Modeling Studies, Craig B. Forster, James P. Evans

Geosciences Faculty Publications

Field, laboratory, and modeling studies of faulted rock yield insight into the hydraulic character of thrust faults. Late‐stage faults comprise foliated and subparallel faults, with clay‐rich gouge and fracture zones, that yield interpenetrating layers of low‐permeability gouge and higher‐permeability damage zones. Laboratory testing suggests a permeability contrast of two orders of magnitude between gouge and damage zones. Layers of differing permeability lead to overall permeability anisotropy with maximum permeability within the plane of the fault and minimum permeability perpendicular to the fault plane. Numerical modeling of regional‐scale fluid flow and heat transport illustrates the impact of fault zone hydrogeology on …

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Wyoming Wilderness Study Report Statewide Overview, United States Bureau Of Land Management Jan 1991

Wyoming Wilderness Study Report Statewide Overview, United States Bureau Of Land Management

All U.S. Government Documents (Utah Regional Depository)

The BLM began the wilderness review in accordance with the requirements of Section 603(c) of the Federal Land Policy and Management Act (FLPMA) dated October 21, 1976. This Act mandated that within 15 years the BLM would inventory and study its lands for their wilderness suitability and that based on this review, the Secretary of Interior would forward his wilderness recommendations to the President.

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Flood Insurance Study, City Of Bountiful, Utah, Davis County, Federal Emergency Management Agency Jan 1991

Flood Insurance Study, City Of Bountiful, Utah, Davis County, Federal Emergency Management Agency

All U.S. Government Documents (Utah Regional Depository)

This Flood Insurance Study revises and updates a previous Flood Insurance Study/Flood Insurance Rate map for City of Bountiful, Davis County, Utah. This information will be used by the City of Bountiful to update existing floodplain regulations as part of the Regular Phase of the National Flood Insurance Program (NFIP). The information will also be used by local and regional planners to further promote sound land use and floodplain development.

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Surficial Geologic Map Of The Oak City Area, Millard County, Utah, United States Geological Survey Jan 1991

Surficial Geologic Map Of The Oak City Area, Millard County, Utah, United States Geological Survey

All U.S. Government Documents (Utah Regional Depository)

This map is preliminary and has not been reviewed for conformity with U.S. Geological Survey editorial standards and stratigraphic nomenclature.

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Fuel Moisture As Measured And Predicted During The 1988 Fires In Yellowstone Park, U.S. Forest Service Jan 1991

Fuel Moisture As Measured And Predicted During The 1988 Fires In Yellowstone Park, U.S. Forest Service

All U.S. Government Documents (Utah Regional Depository)

Fine fuel moisture content, relative humidity, air temperature, and fire behavior were observed hourly for 48 hours on the North Fork fire in Yellowstone National Park from August 25 to August 27, 1988.

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Exxon Wyoming-Dakota Pipeline Segment 2 And Hartzog Draw Unit Co2 Projects Environmental Assessment, United States Department Of The Interior Bureau Of Land Management Jan 1991

Exxon Wyoming-Dakota Pipeline Segment 2 And Hartzog Draw Unit Co2 Projects Environmental Assessment, United States Department Of The Interior Bureau Of Land Management

Environmental Assessments (WY)

This Environmental Assessment (EA) has been prepared to analyze potential impacts from the proposed completion of Segment 2 of the Wyoming-Dakota pipeline and the Hartzog Draw Unit CO2 Project. The impacts of constructing the pipeline were originally analyzed in the Bairoil/Dakota CO2 Project's Environmental Impact Statement (EIS). The Record of Decision for that document was signed in February 1986, and construction on the first segment was completed in September 1986. This EA analyzes the possible environmental and socioeconomic impacts which could result from the proposals, and to solicit public comments and concerns. This document also serves as a request for …

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Competition Between Generic And Nongeneric Fronts Inenvelope Equations, James A. Powell, A. C. Newell, C. K. R. T. Jones Jan 1991

Competition Between Generic And Nongeneric Fronts Inenvelope Equations, James A. Powell, A. C. Newell, C. K. R. T. Jones

James A. Powell

Arguments are presented for understanding the selection of the speed and the nature of the fronts that join stable and unstable states on the supercritical side of first-order phase transitions. It is suggested that from compact support, nonpositive-definite initial conditions, observable front behavior occurs only when the asymptotic spatial structure of a trajectory in the Galilean ordinary differential equation (ODE) corresponds to the most unstable temporal mode in the governing partial differential equation (PDE). This selection criterion distinguishes between a "nonlinear" front, which has its origin in the first-order nature of the bifurcation, and a "linear" front. The nonlinear front …

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Ab Initio Study Of The Intermolecular Potential Of Ar–H2o, G. Chalasinski, M. M. Szczesniak, Steve Scheiner Jan 1991

Ab Initio Study Of The Intermolecular Potential Of Ar–H2o, G. Chalasinski, M. M. Szczesniak, Steve Scheiner

Steve Scheiner

The combination of supermolecular Møller–Plesset treatment with the perturbation theory of intermolecular forces is applied in the analysis of the potential‐energy surface of Ar–H2O. The surface is very isotropic with the lowest barrier for rotation of ∼35 cm−1 above the absolute minimum. The lower bound for De is found to be 108 cm−1 and the complex reveals a very floppy structure, with Ar moving freely from the H‐bridged structure to the coplanar and almost perpendicular arrangement of the C2 –water axis and the Ar–O axis, ‘‘T‐shaped’’ structure. This motion is almost isoenergetic (energy change …

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Ab Initio Study Of Intermolecular Potential Of H2o Trimer, G. Chalasinski, M. M. Szczesniak, P. Cieplak, Steve Scheiner Jan 1991

Ab Initio Study Of Intermolecular Potential Of H2o Trimer, G. Chalasinski, M. M. Szczesniak, P. Cieplak, Steve Scheiner

Steve Scheiner

Nonadditive contribution to the interaction energy in water trimer is analyzed in terms of Heitler–London exchange, SCF deformation, induction and dispersion nonadditivities. Nonadditivity originates mainly from the SCF deformation effect which is due to electric polarization. However, polarization does not serve as a universal mechanism for nonadditivity in water. In the double‐donor configuration, for example, the Heitler–London exchange contribution is the most important and polarization yields the wrong sign. Correlation effects do not contribute significantly to the nonadditivity. A detailed analysis of the pair potential is also provided. The present two‐body potential and its components are compared to the existing …

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Theoretical Vibrational Study Of Fx...Nh3 (X=H, D, Li) Complexes, Y. Bouteiller, Z. Latajka, H. Ratajczak, Steve Scheiner Jan 1991

Theoretical Vibrational Study Of Fx...Nh3 (X=H, D, Li) Complexes, Y. Bouteiller, Z. Latajka, H. Ratajczak, Steve Scheiner

Steve Scheiner

This paper presents the first ab initio attempt to construct the stretching fundamentals νFX and νF...N (X=H, D, Li) in the FX...NH3 complexes taking into account the mechanical anharmonicity. A potential‐energy surface V(rFX,RF...N) grid was generated at the self‐consistent‐field and second‐order Møller–Plesset levels. The coefficients fitting the potential‐energy surface up to the fourth order have been used to compute the νFX and νF...N stretching modes. The vibrational problem is solved by means of a variational treatment which includes the effects of mechanical …

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Effect Of Intermolecular Orientation Upon Proton Transfer Within A Polarizable Medium, Steve Scheiner, X. Duan Jan 1991

Effect Of Intermolecular Orientation Upon Proton Transfer Within A Polarizable Medium, Steve Scheiner, X. Duan

Steve Scheiner

Ab initio calculations are used to investigate the proton transfer process in bacteriorhodopsin. HN = CH2 serves as a small prototype of the Schiff base while HCOO- models its carboxylate-containing counterion and HO- the hydroxyl group of water of tyrosine, leading to the HCOO-.H+.NHCH2 and HO-.H+.NHCH2 complexes. In isolation, both complexes prefer a neutral pair configuration wherein the central proton is associated with the anion. However, the Schiff base may be protonated in the former complex, producing the HCOO-.+HNHCH2 ion pair, when …

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Utah Multihazards Planning Demonstration Project - A Case Study Report, United States Federal Emergency Management Agency Jan 1991

Utah Multihazards Planning Demonstration Project - A Case Study Report, United States Federal Emergency Management Agency

All U.S. Government Documents (Utah Regional Depository)

This report is intended to describe, document, and evaluate the approach used in the Utah Multihazards Mitigation Project (UMP) which culminated in the Utah Plan, and to make that project experience available for use by other State and local governments throughout the nation. The report summarizes the planning and decision-making process followed, describes the specific mitigation measures identified, and assesses the transferability of the Utah approach and requirements for its replication by other State and local governments.

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Beyond The Wasatch: The History Of Irrigation In The Uinta Basin And Upper Provo River Area Of Utah, Gregory D. Kendrick, Charles S. Peterson, National Park Service, Bureau Of Reclamation Jan 1991

Beyond The Wasatch: The History Of Irrigation In The Uinta Basin And Upper Provo River Area Of Utah, Gregory D. Kendrick, Charles S. Peterson, National Park Service, Bureau Of Reclamation

All U.S. Government Documents (Utah Regional Depository)

This book deals with the development of water resources Water, of course, has been one of the great factors tn the growth of the American West . Beyond the Wasatch details the process by which water flowing from the southwest drainages of northern Utah's Uinta Mountains was put to human use. The story belongs primarily to the first half of the 20th century, although parts of it extend to both earlier and later times. The water involved rises within the State of Utah, and its utilization had implications mainly for Utah. Development involved native Americans and the settlement of a …

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Wyoming Statewide Wilderness Study Report, Wilderness Study Area Specific Recommendations, Volume Ii, United States Bureau Of Land Management Jan 1991

Wyoming Statewide Wilderness Study Report, Wilderness Study Area Specific Recommendations, Volume Ii, United States Bureau Of Land Management

All U.S. Government Documents (Utah Regional Depository)

The WSA was studied under section 603 of the Federal Land Policy and Management Act of 1976 (FLPMA) and was included in the Grass Creek/Cody Wilderness Environmental Impact Statement (EIS) filed in August 1990. There were two alternatives analyzed in the EIS, No Wilderness and All Wilderness. The All Wilderness Alternative is the recommendation of this report.

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Wyoming Statewide Wilderness Study Report Wilderness Study Area Specific Recommendations, United States Bureau Of Land Management Jan 1991

Wyoming Statewide Wilderness Study Report Wilderness Study Area Specific Recommendations, United States Bureau Of Land Management

All U.S. Government Documents (Utah Regional Depository)

The recommendation for this WSA is to designate 17,150 acres of BLM land and 1,390 acres of State land as wilderness. This alternative is considered to be the environmentally preferable alternative as it would result in the least change in the natural environment over the long term. The entire 17,150 acres of federal land and 1,390 acres of state land within the WSA are recommended for wilderness designation and are shown on the Bobcat Draw Badlands WSA map. The state lands would be recommended for acquisition to enhance the manageability of the area as wilderness.

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Ab Initio Study Of The Intermolecular Potential Of Ar–H2o, G. Chalasinski, M. M. Szczesniak, Steve Scheiner Jan 1991

Ab Initio Study Of The Intermolecular Potential Of Ar–H2o, G. Chalasinski, M. M. Szczesniak, Steve Scheiner

Chemistry and Biochemistry Faculty Publications

The combination of supermolecular Møller–Plesset treatment with the perturbation theory of intermolecular forces is applied in the analysis of the potential‐energy surface of Ar–H2O. The surface is very isotropic with the lowest barrier for rotation of ∼35 cm−1 above the absolute minimum. The lower bound for De is found to be 108 cm−1 and the complex reveals a very floppy structure, with Ar moving freely from the H‐bridged structure to the coplanar and almost perpendicular arrangement of the C2 –water axis and the Ar–O axis, ‘‘T‐shaped’’ structure. This motion is almost isoenergetic (energy change …

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Theoretical Vibrational Study Of Fx...Nh3 (X=H, D, Li) Complexes, Y. Bouteiller, Z. Latajka, H. Ratajczak, Steve Scheiner Jan 1991

Theoretical Vibrational Study Of Fx...Nh3 (X=H, D, Li) Complexes, Y. Bouteiller, Z. Latajka, H. Ratajczak, Steve Scheiner

Chemistry and Biochemistry Faculty Publications

This paper presents the first ab initio attempt to construct the stretching fundamentals νFX and νF...N (X=H, D, Li) in the FX...NH3 complexes taking into account the mechanical anharmonicity. A potential‐energy surface V(rFX,RF...N) grid was generated at the self‐consistent‐field and second‐order Møller–Plesset levels. The coefficients fitting the potential‐energy surface up to the fourth order have been used to compute the νFX and νF...N stretching modes. The vibrational problem is solved by means of a variational treatment which includes the effects of mechanical …

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