| Scanning Tunneling Microscopic Characterization of an Engineered Organic Molecule |
Aug 2011 |
22 pages |
| Authors:
Govind Mallick; Pamela Kaste; Shashi P Karna; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD VEHICLE TECHNOLOGY DIRECTORATE
|
 | Surface topology and electron transport properties of self-assembled monolayer (SAM) of an engineered molecule 4,4'-[1,4-phenylenebis(methylidynenitrilo)]bisbenzenethiol (PMNBT) and 1-dodecanethiol (dDT) adsorbed on Au substrates have been investigated by scanning tunneling microscopy (STM) at ambient conditions. The electrical measurements of hexadecanethiol (hDT), which is similar in length to PMNBT, have also been compared. The pi-bond dominated PMNBT molecule was engineered using first-principle ab initio molecular orbital theory. The estimated conductance, (dI/dV)v=0.75 = ... |
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| Using Attosecond Technology to Image Molecular Orbitals |
20 Feb 2010 |
3 pages |
| Authors:
Paul Corkum; NATIONAL RESEARCH COUNCIL OF CANADA OTTAWA (ONTARIO)
|
| Attosecond hole dynamics: While studying the spectrum of the high harmonics produced from CO2, we discovered that multiple orbitals can ionize at the same time. This was an unexpected result suggesting that tunneling often launches attosecond dynamics. This research, including an image of the wave packet motion, was published in Nature. Imaging orbitals via tunneling: To gain additional insight into the ionization of lower orbitals, we measured the ionization probability ... |
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| In Silico Pharmacophore Model for Tabun-Inhibites Acetylcholinesterase Reactivators: A study of Their Stereoelectronic Properties |
Jan-2009 |
12 pages |
| Authors:
Apurba K Bhattacharjee; Kamil Kuca; Kamil Musilek; Richard K Gordon; WALTER REED ARMY INST OF RESEARCH SILVER SPRING MD
|
| Organophosphorus (OP) nerve agents that inhibit acetylcholinesterase (AChE; EC 3.1.1.7) function in the nervous system, causing acute intoxication. If untreated, death can result. Inhibited AChE can be reactivated by oximes, antidotes for OP exposure. However, OP intoxication caused by the nerve agent tabun (GA) is particularly resistant to oximes, which poorly reactivate GA-inhibited AChE. In an attempt to develop a rational strategy for the discovery and design of novel reactivators ... |
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| Electron Transport in Boron Fullerenes |
Aug-2008 |
4 pages |
| Authors:
Haiying He; Ravindra Pandey; Ihsan Boustani; Shashi P Karna; MICHIGAN TECHNOLOGICAL UNIV HOUGHTON DEPT OF PHYSICS
|
| The electron transport properties of B80 fullerene are studied using first-principles density functional theory in conjunction with the Landauer-Buettiker quantum transport formalism. The electron transmission in B80 fullerene is calculated to be much higher than that in C60 fullerene in the Fermi-level region. The enhanced transmission in the B80 fullerene is attributed to its spatially extended charge distribution in delocalized bonds. |
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| Methods and Applications of Computational Chemistry |
04 JUL 2007 |
107 pages |
| Authors:
JACKSON STATE UNIV MS
|
| Conference papers on the subjects of computational chemistry, molecular biology, molecular structure, crystallography, and single crystals (abstracts only). |
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| The Electronic Structure and Field Effects of an Organic-Based Room Temperature Magnetic Semiconductor |
01-Jan-2007 |
148 pages |
| Authors:
Derek M Lincoln; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH
|
| The future of spin-electronics or "spintronics" lies in the development of viable magnetic semiconductors that can effectively operate at room temperature Vanadium tetracyanoethylene (V[TCNE]~2) is a magnetic semiconductor with an ordering temperature well above that of room. Its highly disordered structure has hampered a comprehensive description of the interactions between the V and TCNE sublattices that give rise to its magnetic and electrical properties. We report the results of high-resolution ... |
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| Local Bonding Analysis of the Valence and Conduction Band Features of TiO2 |
Jan-2007 |
8 pages |
| Authors:
L Fleming; C C Fulton; G Lucovsky; J E Rowe; M D Ulrich; J Luening; NORTH CAROLINA STATE UNIV AT RALEIGH DEPT OF PHYSICS
|
| An analysis of the valence and conduction band electronic structure of TiO2 as studied by ultraviolet photoemission spectroscopy UPS and x-ray absorption spectroscopy XAS using synchrotron radiation is reported. Valence band spectra from UPS have been deconvolved using a five-peak model. The spectra are interpreted based on the peak assignments to the XAS data and the symmetries of the valence band states. The interpretation is consistent with theoretical calculations of ... |
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| The Convergence of CASSCF-CISD Energies to the Complete Basis Set Limit |
16 FEB 2006 |
30 pages |
| Authors:
George A. Petersson; David K. Malick; Michael J. Frisch; Braunstein Matthew; SPECTRAL SCIENCES INC BURLINGTON MA
|
| Examination of the convergence of full valence CASSCF-CISD energies with expansion of the one-electron basis set reveals a pattern very similar to the convergence of single determinant CCSD energies. Calculations on the lowest four singlet states and the lowest four triplet states of N2 with the sequence of ntuple-zeta augmented polarized (nZaP) basis sets (n = 2,3,4,5, and 6) are used to establish the complete basis set (CBS) limits. Full ... |
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| Determination of Chromium Valence Over the Range Cr(0)-Cr(VI) by Electron Energy Loss Spectroscopy |
2006 |
14 pages |
| Authors:
Tyrone L. Daulton; Brenda J. Little; NAVAL RESEARCH LAB STENNIS SPACE CENTER MS MARINE GEOSCIENCES DIV
|
| Chromium is a redox active 3d transition metal with a wide range of valences (-2 to + 6) that control the geochemistry and toxicity of the element. Therefore, techniques that measure Cr valence are important bio/geochemical tools. Until now, all established methods to determine Cr valence were bulk techniques with many specific to a single, or at best, only a few oxidation state(s). We report an electron energy loss spectroscopy ... |
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| Total Ionization Cross Sections of Molecules by Electron Impact |
08 JUN 2005 |
11 pages |
| Authors:
Yong-Ki Kim; NATIONAL INST OF STANDARDS AND TECHNOLOGY GAITHERSBURG MD
|
| The theoretical basis for the binary-encounter-Bethe (BEB) model is outlined, and the model is compared to available experiments and other theories for samples of stable molecules, radicals, and positive ions. Possible directions for improving the BEB model also are presented. The BEB model does not contain empirical parameters, offers a simple equation and recipe for the ionization cross-section of individual molecular orbitals, and provides reliable cross-sections at low as well ... |
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| The Convergence of CASSCF Energies to the Complete Basis Set Limit |
APR 2005 |
18 pages |
| Authors:
George A. Petersson; David K. Malick; Michael J. Frisch; Matthew Braunstein; WESLEYAN UNIV MIDDLETOWN CT HALL-ATWATER LABS
|
| Examination of the convergence of full valence CASSCF energies with expansion of the one-electron basis set reveals a pattern very similar to the convergence of single determinant Hartree-Fock energies. Calculations on twenty-six molecular examples with the sequence of ntuple-sigma augmented polarized (nZaP) basis sets (n = 2, 3, 4, 5, and 6) are used to evaluate complete basis set (CBS) extrapolation schemes. The most effective extrapolation reduces the RMS one-electron ... |
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| Quantitative Structure-Property Relationships for Melting Points and Densities of Ionic Liquids |
JUL 2004 |
22 pages |
| Authors:
Steven Trohalaki; Ruth Pachter; Greg W. Drake; Tommy Hawkins; ANTEON CORP DAYTON OH
|
| Although innumerable different ionic liquids are possible, even basic physical-property data, such as the density and melting point, exist only for relatively few. Derivation of melting point QSPRs (Quantitative Structure- Property Relationships) for energetic ionic liquids would therefore greatly aid in the molecular design of new compounds. A new class of ionic liquids, based on 1-substituted-4-amino-1,2,4-triazolium bromide and nitrate salts, were recently synthesized and their melting points and densities measured. ... |
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| Preparation and Characterization of the First Binary Titanium Azides, Ti(N3)4, P(C6H5)4Ti(N3)5 and P(C6H5)42Ti(N3)6 and on Linear Ti-N-NN Coordination |
12 MAR 2004 |
21 pages |
| Authors:
Karl O. Christe; Ralf Haiges; Stefan Schneider; Thorsten Schroer; Jerry A. Boatz; ENGINEERING RESEARCH AND CONSULTING INCHUNTSVILLE AL
|
| Where as numerous partially azide-substituted titanium compounds had previously been reported, 1-7 no binary titanium azides were known. In a recent theoretical study the group 4 metal tetrazides M(N3)4 (M = Ti, Zr, Hf, Th) were predicted 8 to be vibrationally stable exhibiting tetrahedral structures with unique linear M-N-NN bond angles (see Figure 1). All previously characterized covalent binary azide species possess bent M-N-NN angles. In this paper we wish ... |
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| Polynitrogen Chemistry |
21 APR 2003 |
3 pages |
| Authors:
Karl Christie; William Wilson; Ashwani Vij; Vandana Vij; Robert Corley; ENGINEERING RESEARCH AND CONSULTING INC(ERC INC) EDWARDS AFB CA
|
| Under combined DARPA, AFOSR, NSF, and DOE sponsorship, we have continued our work in polynitrogen chemistry. We have successfully prepared and characterized numerous polyazido compounds, such as As(N3)3, Sb(N3)3, As(N3)5, Sb(N3)5, As(N3)6(-), Sb(N3)6(-), Te(N3)4, Te(N3)6(2-) P(N3)6(-), and B(N3)4(-), and have studied the combination of N5(+) with some of these among. Most of these compounds are extremely energetic and shock sensitive. We have studied the reactions of the NF4(+) and N2F3(+) ... |
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| Enthalpies of Formation of Gas Phase N3, N3(-), N3(+), and N5(-) from Ab Initio Molecular Orbital Theory, Stability( Predictions for N5(+) N3(-) and N5(+) N5(-), and Experimental Evidence for the Instability of N5(+) N3(-) |
2003 |
36 pages |
| Authors:
David A. Dixon; Davied Feller; Karl O. Christe; William W. Wilson; Ashwani Vij; ENGINEERING RESEARCH AND CONSULTING INC(ERC INC) EDWARDS AFB CA
|
| Ab initio molecular orbital theory has been used to calculate accurate enthalpies of formation and adiabatic electron affinities or ionization potentials for N3, N3(-), N5(+), and N5(-) from total atomization energies. Born-Haber cycle calculations, using estimated lattice energies and the adiabatic ionization potentials of the anions and electron affinities of the cations, permit for the first time reliable stability predictions for the hypothetical N5(+) N3(-) and N5(+)N5(-) salts. Contrary to ... |
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| Theoretical Studies of Gas Phase Elementary Reactions |
17 AUG 2001 |
19 pages |
| Authors:
Keiji Morokuma; EMORY UNIV ATLANTA GA DEPT OF CHEMISTRY
|
| This final technical report begins with the objective, followed by detailed reports on new accomplishments and new findings obtained in the project. They are presented in six sections: (A) Potential Energy Surfaces of Ion-Molecule Reactions, (B) Potential Energy Surfaces of Ions, (C) Potential Energy Surfaces for Photochemical Reactions and Nonadiabatic Processes, (D) potential Energy Surfaces of Open-Shell Molecules, (E) Dynamics and Kinetics in the Ground Electronic State, and (F) Potential ... |
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| Determination of the Orbital Lineup at Reactive Organic Semiconductor Interfaces Using Photoemission Spectroscopy |
02 APR 2001 |
9 pages |
| Authors:
R. Schlaf; C. D. Merritt; L. C. Picciolo; Z. H. Kafafi; UNIVERSITY OF SOUTH FLORIDA TAMPA DEPT OF ELECTRICAL ENGINEERING
|
| We determined the orbital lineup of the tris (8-hydroxyquinolinato) gallium (Gaq3)/Mg interface using combined x-ray and ultraviolet photoemission spectroscopy (XPS and UPS) measurements. The Gaq3 /Mg system is a prototypical model structure for organic electron/low work function electrode transporting materials interfaces found in organic light emitting diodes (OLED). A Gaq3 thin film was grown in 15 steps on a previously sputter-cleaned Mg substrate starting at a 1 nominal thickness up ... |
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| Theoretical Studies of Solid Nitromethane |
FEB 2001 |
26 pages |
| Authors:
Dan C. Sorescu; Betsy M. Rice; Donald L. Thompson; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| A classical potential to simulate the dynamics of a nitromethane crystal as a function of temperature and pressure is described. The intramolecular part of the potential was taken as superposition of bond stretching, bond bending, and torsional angles terms. These terms were parametrized on the basis of the geometric and spectroscopic (vibrational frequencies and eigenvectors) data obtained using ab initio molecular orbital calculations performed at the B3LYP/6-3 1 G level ... |
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| 2001 Gordon Research Conference on Molecular Energy Transfer |
JAN 2001 |
14 pages |
| Authors:
Carlyle B. Storm; GORDON RESEARCH CONFERENCES INC KINGSTON RI
|
| The Gordon Research Conference (GRC) on Molecular Energy Transfer was held at Harbortown Resort, Ventura, California January 14-19, 2001. The conference was well attended with 89 participants (list enclosed). The attendees represented the spectrum of endeavor in this field coming from academia, industry, and government laboratories, both US and foreign scientists, senior researchers, young investigators, and students. In designing the formal speakers program, emphasis was placed on current unpublished research ... |
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| Overview of Molecular Modelling and Ab initio Molecular Orbital Methods Suitable for Use with Energetic Materials |
SEP 2000 |
|
| Authors:
H. Dorsett; A. White; DEFENCE SCIENCE AND TECHNOLOGY ORGANIZATION SALISBURY (AUSTRALIA)
|
 | This is a review of molecular modelling techniques which may be applied to studies of energetic materials. It focuses on ab initio (first- principles') molecular orbital calculations, since these methods offer the greatest accuracy. Since ab initio calculations are very computer-intensive, approximate MO methods are also discussed, which offer reasonably accurate predictions with reduced calculation times. These approximate methods include density functional theory and ... |
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| Computational Studies of FOX-7, A New Insensitive Explosive |
SEP 2000 |
|
| Authors:
Helen Dorsett; DEFENCE SCIENCE AND TECHNOLOGY ORGANIZATION SALISBURY (AUSTRALIA)
|
| First-principles quantum chemical calculations are used to predict the initial steps of decomposition in solid FOX-7 (1,1-diamino-2,2- dinitroethylene). Three possible reaction paths were studied: (1) intra- or inter-molecular hydrogen transfer; (2) nitro-nitrite rearrangement and (3) scission of the C-nitro bond. These computational studies suggest that the preferred path for FOX-7 decomposition will depend upon the conditions which cause initiation. For example, under gentle ... |
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| High Magnetic Field Dependence of the Edge and Bulk State Electron Transport in Single-Crystalline Tungsten Nanostructures |
23 JUN 2000 |
4 pages |
| Authors:
G. M. Mikhailov; A. V. Chernykh; J. C. Maan; J. G. Lok; A. K. Geim; RUSSIAN ACADEMY OF SCIENCES CHERNOGOLOVKA INST OF MICROELECTRONICS AND HIGH PURITY MATERIALS
|
| Electron conductivity of single crystalline nanostructures both of bridge- and cross- type has been investigated at 4.2 K. It shows strong dependence in magnetic field and also exhibits anisotropy against magnetic field direction. It was found new reentrance effect in ballistic properties of multi-terminal cross-type nanostructure. where ballistic properties are suppressed in moderate magnetic field and restored again at higher field. |
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| Phase Coherent Electron Transport in Open Quantum Dots and Quantum Dot Arrays |
23 JUN 2000 |
6 pages |
| Authors:
J. P. Bird; R. Akis; D. K. Ferry; M. E. Hassen; A. Shailos; ARIZONA STATE UNIV TEMPE
|
| Recent studies of coherent electron transport in open quantum dots and quantum dot arrays are reviewed. Our interest focuses on the connection between the quantum and semi-classical descriptions of transport in these Structures, which provide ideal systems for the experimental study of quantum chaos. |
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| Theoretical Studies of Gas Phase Elementary Reactions |
SEP 1998 |
18 pages |
| Authors:
Keiji Morokuma; EMORY UNIV ATLANTA GA
|
| Understanding the mechanism, kinetics and dynamics of elementary gas phase reactions is one of the major goals of chemistry. Such understanding is also essential to predicting and understanding plasma dynamics and optical radiation associated with the spacecraft-atmosphere interactions. The objective of the present research was to provide, based on mainly the ab initio molecular orbital and some dynamics calculations, theoretical information concerning the potential ... |
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| Nanometric Studies of the Structure and Tribology of Carbon Nitride Materials |
31 JUL 1998 |
10 pages |
| Authors:
Charles M. Lieber; HARVARD UNIV CAMBRIDGE MA DEPT OF CHEMISTRY AND CHEMICAL BIOLOGY
|
| Significant effort has been placed on several areas. First, we have carried out systematic studies of the growth of carbon nitride materials as a function of carbon reactant energetics, nitrogen flux and growth temperature and have quantitatively analyzed the structure and local bonding in these materials. The emphasis of these studies has been to determine unambiguously conditions that can produce sp3-bonding since this is required for a ... |
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| A Comparative Analysis of Hartree-Fock and Kohn-Sham Orbital Energies |
27 APR 1998 |
15 pages |
| Authors:
Peter Politzer; Fakher Abu-Awwad; NEW ORLEANS UNIV LA DEPT OF CHEMISTRY
|
| Hartree-Fock and Kohn-Sham orbital energies, the latter computed with several different exchange correlation functionals are compared and analyzed for twelve molecules. The Kohn-Sham energies differ significantly from experimental ionization energies, but by amounts that are, for a given molecule and exchange correlation functional, roughly the same for all of the valence orbitals. With the exchange correlation functionals used, the energy of the highest occupied Kohn-Sham orbital does not approximate the ... |
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| Some Approximate Kohn-Sham Molecular Energy Formulas |
27 APR 98 |
20 pages |
| Authors:
Peter Politzer; Fakher Abu-Awwad; NEW ORLEANS UNIV LA DEPT OF CHEMISTRY
|
| Density functional calculations have been carried out for twelve molecules by several different Kohn-Sham procedures in order to test the effectiveness of two approximate molecular energy formulas that have been applied earlier in the context of Hartree-Fock theory. The equation E(molecular) = 3/7( (Vne + 2Vnn), in which Vne and Vnn are the nuclear-electronic attraction and nuclear repulsion, reproduces Kohn-Sham energies with an average deviation of less than 0.70%. E(molecular) ... |
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| New Concepts in Electron Correlation with Application to Extended Systems |
APR 98 |
10 pages |
| Authors:
Rodney J. Bartlett; FLORIDA UNIV GAINESVILLE
|
| The objective of our work for ONR has been to develop and apply new, correlated electronic structure methods for infinite periodic systems. The methods of interest include many body perturbation theory (MBPT) and its infinite order coupled cluster generalizations and complementary density functional methods. Today we routinely do highly correlated studies of molecules (including making reliable predictions of structure, photoelectron, vibrational, and electronic spectra). The next frontier in electronic structure ... |
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| Computationally Efficient Models for the Calculation of Structures and Properties of Materials |
18 MAR 1998 |
17 pages |
| Authors:
Peter Pulay; ARKANSAS UNIV FAYETTEVILLE DEPT OF CHEMISTRY
|
| The goal of this research was to develop efficient methods for the determination of structures of complex molecular systems. Both the optimization strategy (1), and the generation of accurate potential energy functions (2) were addressed. Under (1), the PI concentrated on the role of coordinates adapted to molecular potential surfaces. His coordinates are widely used for medium-sized molecules where their rapid convergence greatly outweighs their extra cost. However, for large ... |
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| Proceedings of the International Symposium on Atomic, Molecular, and Condensed Matter Theory, Volume 70, No. 4/5 |
FEB 1998 |
|
| Authors:
Per-Olov Loewdin; Yngve Oehrn; John R. Sabin; Michael C. Zerner; FLORIDA UNIV GAINESVILLE QUANTUM THEORY PROJECT
|
| The 38th Annual Sanibel Symposium, organized by the faculty, students, and staff of the Quantum Theory Project of the University of Florida, was held on February 21-27, 1998. Again, the Ponce de Leon Conference Center in St. Augustine, Florida, was the site of the gathering of more than 300 scientists. The symposium followed the established format with plenary and poster sessions. A compact 7-day integrated ... |
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| Energy Transfer Processes in Iodine Lasers |
28 DEC 1997 |
32 pages |
| Authors:
Michael C. Heaven; EMORY UNIV ATLANTA GA
|
| The near resonant electronic energy transfer process I(2P3/2) + O2(alpha) left & right arrow I(2P1/2) + O2(X) is of central importance in COIL systems. The low temperature kinetics were characterized by studies of I(2P1/2) +O2 quenching at temperatures near 150K. As a component of this effort, sensitive LIF detection of I(2P1/2) was demonstrated. A quenching rate constant of (4.5+/-0.5)x10(exp -12 cu cm /s was obtained, which was appreciably smaller than ... |
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| Application of the Optimized Effective Potential Method to Quantum Chemistry |
11 NOV 1997 |
11 pages |
| Authors:
Joseph B. Krieger; BROOKLYN COLL NY
|
| In this final year of the grant period, we have concentrated our efforts in three areas: (1) The determination of the exact exchange mixing parameter by requiring that the ionization energy theorem for atoms with Z less than or equal 20 be satisfied as closely as possible, (2) the completion of the application of Kohn-Sham Theory for Orbital Dependent (Self-Interaction- Corrected) Exchange-Correlation Energy Functionals to Diatomic Molecules, and (3) The ... |
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| Student Travel Support for Gordon Research Conference on Molecular Energy Transfer |
JUN 97 |
5 pages |
| Authors:
Marshal Lester; GORDON RESEARCH CONFERENCES INC KINGSTON RI
|
| The Gordon Research Conference (CRC) on MOLECULAR ENERGY TRANSFER was held in Ventura, California at HOLIDAY INN from 1/5/97 thru 1/10/97. The conference was well-attended with 117 participants (attendees list attached). The attendees represented the spectrum of endeavor in this field coming from academia, industry, and government laboratories, both U.S. and foreign scientists, senior researchers, young investigators, and students. |
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| A NEXAFS Study on the Coordination Geometry of Aluminum in Minerals and Y Zeolite. Comparison of Experiment and Theory |
JAN 97 |
9 pages |
| Authors:
J. A. Van Bokhoven; H. Sambe; D. C. Koningsberger; D. E. Ramaker; GEORGE WASHINGTON UNIV WASHINGTON DC DEPT OF CHEMISTRY
|
| Curved-wave multiple scattering cluster calculations using the FEFF6 code were successfully used to interpret experimental Al K edge NEXAFS spectra of various minerals and Y zeolites. starting about 5 eV above threshold. The Al octahedral, tetrahedral and square planar geometries can be easily distinguished from each other utilizing the NEXAFS data. Semi-empirical molecular orbital calculations were used to interpret the whitelines below 5 eV in the data. A new assignment ... |
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| Crystal Structure, Reactivity, and Photochemical Properties of Tungsten(0) Zwitterionic Amido Complex (CO)5 WNPhNPhC(OMe)Ph |
MAY 96 |
32 pages |
| Authors:
Scott T. Massey; Nicholas D. Barnett; Khalil A. Abboud; Lisa McElwee-White; FLORIDA UNIV GAINESVILLE DEPT OF CHEMISTRY
|
| The crystal structure of the zwitterionic complex (CO)5WNPhNPhC(Ph) OMe (1) shows that it is best described as an amido complex in which the 'imidate' fragment PhN=C(Ph)OMe serves as a substituent on the amide nitrogen. The structural information allows the previously reported conversion of 1 to an isomeric zwitterion to be assigned as simple rotation about the N-C double bond. The twisted intermediate for such a rotation also offers a pathway ... |
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| Anomalous Magnetoresistance in the Lanthanide Manganites and Its Relation to High-Tc Superconductivity |
MAY 96 |
|
| Authors:
G. F. Dionne; MASSACHUSETTS INST OF TECH LEXINGTON LINCOLN LAB
|
| A theory of electron transport is formulated from the polaronic and magnetic exchange character of mixed-valence transition metal oxides. Where magnetic ordering is established at low temperatures, the conduction is mainly by polarons. Above the curve temperature Tc, electron hopping by thermal activation becomes dominant. The conventional relations for mobility-activated semiconduction anti the molecular field theory of ferromagnetism are adapted for interpretation of electrical resistivity p data of the lanthanitle ... |
|
| Electronic Structure and Spectroscopy of Cadmium Sulfide Clusters |
12 FEB 96 |
41 pages |
| Authors:
Hui-Jean Liu; Joseph T. Hupp; Mark A. Ratner; NORTHWESTERN UNIV EVANSTON IL DEPT OF CHEMISTRY
|
| There has been extensive study, both experimentally and theoretically, on how a semiconductor nanocrystal evolves to a bulk material and how its corresponding electronic properties change. Experimental observations show a close relationship between the size of nanocrystals, the lowest energy optical absorption peak and the highest energy band of the luminescence spectrum. These are usually assigned to the transition between the valence band and the conduction band or, in the ... |
|
| Anionic Lewis Acids. A Chemical Oxymoron |
17 OCT 95 |
15 pages |
| Authors:
Larry A. Dominey; Richard Laura; Wayne J. Clark; Tom J. Blakley; Warren Averill; COVALENT ASSOCIATES INC WOBURN MA
|
| An emerging class of unusual compounds Anionic Lewis Acids was the center of study in this research program. We carried out ab initio molecular orbital calculations on two of these anions, (CF3SO2)2N(-), and (CF3SO2)3C(-). A multi-nuclear FT-NMR study was conducted on a series of anions and the results could be rationalized on the number of substituents present in the anions. In addition, a new anionic Lewis acid was synthesized and ... |
|
| Collisional Dynamics of the Rubidium 5(2)P Levels |
AUG 95 |
131 pages |
| Authors:
Matthew D. Rotondaro; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH
|
| The collisional dynamics of the 5(2)P levels in rubidium has been examined using steady-state laser absorption nd spectrally-resolved laser induced fluorescence techniques. State-to-state cross-sections for energy transfer between Zeeman split levels ranged from 16-248 A2 for collisions with nitrogen and rare gases. These energy transfer cross-sections exhibit a significant dependence on (J,mj) state and certain symmetry relationships are demonstrated. A sub-Doppler spectrum of the Zeeman split levels indicating the isotopic ... |
|
| Excited Electronic States of Energetic Materials - Structure, Dynamics, Reactivity |
05 JUL 95 |
7 pages |
| Authors:
Elliot R. Bernstein; COLORADO STATE UNIV FORT COLLINS
|
| In this work we have studied the properties of Rydberg states of amines and ethers with a view to their application to and importance for the chemistry of energetic materials. We have learned that in clusters these Rydberg states can be quite reactive and, in fact, they dominate the excited state chemistry and dynamics through electron transfer reactions. This unexpected and new phenomenon can be understood based on available excited ... |
|
| Calculated Structures and Electronic Absorption Spectroscopy for Magnesium Phthalocyanine and its Anion Radical |
19 APR 95 |
39 pages |
| Authors:
Marshall G. Cory; Horoaki Hirose; Michael C. Zerner; FLORIDA UNIV GAINESVILLE DEPT OF CHEMISTRY
|
| Structures are calculated for Magnesium Phthalocyanine (MgPc) and its radical anion doublet (MgPc-), using both ab-initio (6-13G**) and semiemperical (INDO/1) self-consistent field approaches. The anion is first order Jahn-Teller distorted, and the various distortions that are possible are examined. The electronic absorption spectra of both molecular species, and the effect varying the degree of distortion has on the computed anion spectrum are discussed. These results suggest that the four-orbital model ... |
|
| Effects of Molecular Structure on the Electroactive and Optical Properties of Conjugated Rigid-Rod Polybenzobisazoles |
20 MAR 95 |
55 pages |
| Authors:
John A. Osaheni; Samson A. Jenekhe; ROCHESTER UNIV NY DEPT OF CHEMICAL ENGINEERING
|
| The effects of molecular structure on the electronic structure and electrochemical and linear optical properties of a series of pi-conjugated rigid-rod polybenzobisazoles, including three new polymers, were explored by cyclic voltammetry and measurement of the optical dispersion of the refractive index. The electrochemical reduction of the polymers was reversible whereas oxidation was not reversible in accord with the electron deficient nature of the benzobisazole ring. The observed variation of the ... |
|
| Molecular Modeling of PMN Ceramics |
23 JAN 95 |
42 pages |
| Authors:
George J. Kavarnos; NAVAL UNDERSEA WARFARE CENTER NEWPORT DIV NEW LONDON CT NEW LONDON DETACHMENT
|
| Extended HOeckel theory was used to analyze the orbital interactions in PbNbO3(+) and LaNbO3(2+) model structures representative of lead magnesium niobate (PMN )ceramic. These structures were chosen to determine the orbital effects, if any, that an A-site substitutional such as Pb(2+) has on bond stability in the crystal lattice structure. It was determined that the A-site ion does not directly influence bonding between the A-site ion and atoms in the ... |
|
| The Mechanism of Catalytic Hydrocarbon Oxidation by Molecular Oxygen and Halogenated Ruthenium and Iron Porphyrins |
95 |
365 pages |
| Authors:
Eva R. Birnbaum; AIR FORCE RESEARCH LAB BOLLING AFB DC
|
| Highly halogenated ruthenium and iron porphyrins are shown to be active catalysts for alkene oxidation with dioxygen or iodosobenzene. The synthesis and characterization of beta-octachloro-tetrakis (pentafluorophenyl) porphyrinato-ruthenium(II) carbonyl RuTFPPCl8(CO) and beta -octabromo- tetrakis(pentafluorophenyl)porphyrinato- iron(III) chloride Fe(TFPPBr8)Cl are reported. Crystal structures of RuTFPPCl8(CO) and the zinc and free ligand precursor complexes show extensive distortion of the halogenated porphyrin macrocycles due to steric interactions between the beta-chlorine atoms and the pentafluorophenyl rings. ... |
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| Quantum Chemical Study of Rare Gas/Halide Interactions as a Model for High Energy Density Material: 2. The Interaction of Hydrogen Chloride with the Rare Gas Xenon |
NOV 94 |
41 pages |
| Authors:
George F. Adams; Cary F. Chabalowski; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
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| Electronic transitions from laser excitation have produced charge transfer (CT) reactions in doped xenon solids, which in turn generate spatially separated, long-lived, dipolaron states. These quasi-stable separated charges have been as an energy storage mechanism in the study of high-energy density materials. In a previous study, we performed calculations on selected singlet electronic state of HC1, and in this study we investigate the character of the low-lying singlet electronic states ... |
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| SAM1 Semiempirical Parameters |
10 AUG 94 |
7 pages |
| Authors:
Andrew J. Holder; MISSOURI UNIV-KANSAS CITY DEPT OF CHEMISTRY
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| Elemental parameter sets have been completely developed and validated for sulfur (S), silicon (Si), and phosphorous (P). They are a significant improvement over previous models. Extensive work has been completed on SAM1 parameters for iron (Fe), preliminary results are available. Substantial obstacles have been overcome in the iron work and a clear route to the objective has been established. The theoretical framework is in place and all that is required ... |
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| Theoretical Interpretation of the Fluorescence Spectra of Toluene and P- Cresol |
JUL 94 |
24 pages |
| Authors:
James O. Jensen; Hendrik F. Hameka; BATTELLE MEMORIAL INST COLUMBUS OH
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| The fluorescence spectra of toluene and p-cresol from ab initio calculations were interpreted on the ground states and the lowest excited singlet states of the two molecules. Determination was made on the energy minima and the optimized geometries of the ground states and the lowest excited singlet states from 4 in 4 CASSCF computations using 6-31G basis set. Also computed was the vibrational frequencies of both molecules in the two ... |
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| Periodicity and Peculiarity in 120 First and Second Row Diatomic Molecules |
22 APR 94 |
55 pages |
| Authors:
A. I. Boldyrev; N. Gonzales; J. Simons; UTAH UNIV SALT LAKE CITY DEPT OF CHEMISTRY
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| The ground and very low-lying excited states of all 120 first and second row diatomic molecules are surveyed. Three quarters of these molecules have had their ground state term symbols reliably experimentally determined. However, one quarter remain predicted only theoretically. For all 120 species, the best available experimental (where known) and theoretical values for the dissociation energies to ground-state atoms are also presented. The Aufbau principle, combined with standard energy ... |
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| Laser Spectroscopy of Gdo: Ligand Field Assignments of 4f7(8S)6p Reversing 4f7(8)6s Transitions |
94 |
13 pages |
| Authors:
Leonid A. Kaledin; Matthew G. Erickson; Michael C. Heaven; EMORY UNIV ATLANTA GA
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| Wavelength-resolved fluorescence excitation techniques have been used to record three electronic transitions of GdO at a resolution of 0.03/cm1. Previous analyses of two bands have been extended with some corrections to the assignments of low-J lines. Improved molecular constants were obtained for the X9(sigma)- and a7(sigma)- states that correlate with Gd2+(4f7((8S)6s)02-. A large difference between the spin-orbit coupling constants for X9(Sigma)-(Lambda = -0.10353/cm)and a7(Sigma)-(Lambda = 0.64712/cm) was noted. This difference ... |
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| Electron-Nuclear Dynamics of Molecular Systems |
94 |
16 pages |
| Authors:
Agustin Diz; Yngve Ohrn; FLORIDA UNIV GAINESVILLE QUANTUM THEORY PROJECT
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| The content of an ab-initio time-dependent theory of quantum molecular dynamics of electrons and atomic nuclei is presented. Employing the time-dependent variational principle and a family of approximate state vectors yields a set of dynamical equations approximating the time-dependent Schrodinger equation. These equations govern the time evolution of the relevant state vector parameters as molecular orbital coefficients, nuclear positions and momenta. This approach does not impose the Born-Oppenheimer approximation, does ... |
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Reports by Keyword(s)
MOLECULAR ORBITALS
