Physical Sciences and Mathematics Commons^™

Theoretical Studies Of Silabicyclobutanes And Silacyclobutenes, Cnsi4-Nh6 (N = 0-4), Jerry A. Boatz, Mark S. Gordon

Mark S. Gordon

The geometries of the silicon-substituted bicyclobutanes and cyclobutenes c.Si4-.H6 are predicted by using the 3-21G(d) basis set and SCF wave functions. Strain energies and heats of formation are predicted by using MP2/6-31G(d) energies in conjunction with the appropriate homodesmic reactions. Bent bond lengths are calculated by tracing the path of maximum electron density connecting two nuclei, with the 6-31 G(2d) basis set at the 3-21 G(d) structures.

Potentially Aromatic Metallocycles, Kim K. Baldridge, Mark S. Gordon

Mark S. Gordon

Ab initio molecular orbital theory is used to characterize a series of metal-substituted benzene and cyclopentadiene structures, with the heteroatom taken from the block in the periodic table bounded by groups IV-VI and periods 2-5. Structures are predicted with the 3-21G* basis set and SCF wave functions. The calculated bond lengths and bond angles are in general within 0.04 A and 2°, respectively, of the available experimental values. As a measure of the de localization stabilization, !::.£and t::..H0 values for the appropriate bond separation and superhomodesmic reactions are calculated with 3-21 G* Hartree-Fock energies for these compounds and some smaller …

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Theoretical Study Of The Decomposition Of Five-Coordinate Silicon Anions, Larry P. David, Larry W. Burggraf, Mark S. Gordon

Mark S. Gordon

We have performed a theoretical study of the decomposition of the five-coordinate silicon anions (siliconates) H3(CH3)SiOH- and (CH3) 4SiOH-. These ions can be formed from hydroxide ion attack on methylsilane or tetramethylsilane, respectively. Both MNDO and ab initio calculations show that removal of methane from the five-coordinate structure is likely, via a transfer of the proton from the OH group to an adjacent methyl substituent. This process we term anionic dissociative proton transfer, because the transition state is one in which the methyl group being removed is almost completely dissociated to methide ion before the proton transfer takes place. This …

Ab Initio Approach To The Deuteron In The Skyrme-Witten Model, Alec Schramm

Alec J Schramm

No abstract provided.

A Calculation Of The Deuteron As A Biskyrmion, Alec Schramm, Yossef Dothan, L. Beidenharn

Alec J Schramm

No abstract provided.

Two Discrete Forms Of The Jordan Curve Theorem, Lawrence N. Stout

Lawrence N. Stout

The Jordan curve theorem is one of those frustrating results in topology: it is intuitively clear but quite hard to prove. In this note we will look at two discrete analogs of the Jordan curve theorem that are easy to prove by an induction argument coupled with some geometric intuition. One of the surprises is that when we discretize the plane we get two Jordan curve theorems rather than one, a consequence of the interplay between two natural products in the category of graphs. Topology in this context has been studied by Farmer in [2]. To state the discrete versions, …

Toeplitz Systems Associated With The Product Of A Formal Laurent Series And A Laurent Polynomial, William F. Trench

William F. Trench

No abstract provided.

Numerical Solution Of The Eigenvalue Problem For Symmetric Rationally Generated Toeplitz Matrices, William F. Trench

William F. Trench

No abstract provided.

Algorithms And Accuracy Requirements For Computing Reaction Paths By The Method Of Steepest Descent, Bruce C. Garrett, Michael J. Redmon, Rozeanne Steckler, Donald G. Truhlar, Kim K. Baldridge, David Bartol, Michael W. Schmidt, Mark S. Gordon

Mark S. Gordon

We present several algorithms for computing minimum energy reaction paths by the method of steepest descents of the potential energy and for interpolating reaction-path potentials. The algorithms are suited for use with global analytic potential surfaces or ab initio calculations of energies and gradients. The efficiencies of the various algorithms are demonstrated and compared by applications to several test cases.

Asymptotic Integration Of A Perturbed Constant Coefficient Differential Equation Under Mild Integral Smallness Conditions, William F. Trench

William F. Trench

No abstract provided.

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Mixed Sublinear, Superlinear, And Singular Systems Of Functional Differential Equations, William Trench

William F. Trench

No abstract provided.

Numerical Simulations Of Narrow Planetary Rings: An Animation, Robert A. Kolvoord, J A. Burns

Robert A Kolvoord

No abstract provided.

Microcomputer In An Introductory College Astronomy Laboratory: A Software Development Project, D D. Meisel, K F. Kinsey, Charles H. Recchia

Charles H Recchia

No abstract provided.

The Magical Computer, David Morgan Lochhead

Dr. David Morgan Lochhead

David Lochhead's speech: "Two years ago, I had the privilege of giving the opening address at the first CAMCON. I opened that address by posing the question "Does God love Computers?" Today I would like to start with a related question. What makes computers loveable? "

Prediction Of Fracture In Patients With Acute Musculoskeletal Ankle Trauma, Paula Diehr

Paula Diehr

X-rays taken for ankle trauma contribute significantly to the cost of health care in this country. In an attempt to find clinical correlates of ankle fracture 36 detailed historical and physical examination variables were collected from 587 consecutive patients with ankle trauma, and ankle x-rays were taken of all patients. The association of each variable with the final diagnosis of fracture, rupture, or sprain was tested; 21 variables were significant predictors of fracture (vs. sprain and rupture) and 15 were not significantly associated with final diagnosis. The variables were used in a linear discriminant analysis to develop a rule which …

Effects Of Chemical And Magnetic Disorder In Fe0.50mn0.50, Duane D. Johnson, F. J. Pinski, G. M. Stocks

Duane D. Johnson

We present the results of first‐principles calculations of the total energy and spin‐polarized electronic structure of disordered fcc Fe0.50Mn0.50. These self‐consistent calculations were performed using the Korringa–Kohn–Rostoker method and the coherent‐potential approximation (KKR‐CPA), using the local‐spin‐density approximation to treat exchange and correlation. We use a lattice constant of a=6.80 a.u.; information about stability can be inferred from calculated pressure and energy. The moments on the Fe and Mn sites are large but antiparallel to each other, resulting in a small net magnetization. A comparison of the electronic structure is made for fcc Fe, Mn, and FeMn in both the ferromagnetic …

Substituted Silabenzenes, Kim K. Baldridge, Mark S. Gordon

Mark S. Gordon

Ab initio calculations have been carried out on a group of substituted monosilabenzenes. Twelve different substituents are considered (Cl, F, SH, OH, PH2, NH2, CH3, SiH3, N02, CN, OCH3, COOH), each placed in the four unique positions on the ring. The relative energies and stabilities, aromaticities (as measured by bond separation reactions), electron density distributions, and dipole moments of these compounds are considered and discussed with the aid of density difference plots.

Structure And Bonding In Cycloalkanes And Monosilacycloalkanes, Jerry A. Boatz, Mark S. Gordon, Richard L. Hilderbrandt

Mark S. Gordon

The structural parameters and vibrational frequencies are predicted for the cycloalkanes C.H2• and silacycloalkanes SiC,_1H2n, n = 3-6, using the 3-21G* basis set and SCF wave functions. Bent bond lengths are predicted by tracing the paths of maximum electron density connecting atomic centers. Strain energies and heats of formation are predicted for these compounds and some smaller acyclic alkylsilanes by using MP2/6-31G(d) energies at the 3-21G* geometries and the appropriate homodesmic reactions.

Theoretical Study Of The Lowest Triplet Potential Energy Surface Of Silasilene, Shiro Koseki, Mark S. Gordon

Mark S. Gordon

Bent silasilene, SiSiH2 (C,, 3A"), which has been reported as a global minimum on the lowest triplet potential energy surface of Si2H2, is found to be higher in energy than planar silasilene (C2v, 3A2) by about 2 kcaljmol at the MP4SDTQ/6-31 ++G(d,p) level, suggesting that triplet silasilene (still the global minimum) must have a planar geometry. Trans-bent HSiSiH (C2h, 3Au) should be the most stable triplet disilyne, instead of the twisted structure reported earlier, while the cis-bent structure (C., 3 A") might be observable.

Theoretical Study Of The Hyperfine Fields Of Ni And Fe In Fcc Ni,Fe, Alloys, H. Ebert, H. Winter, B. L. Gyorffy, Duane D. Johnson, F. J. Pinski

Duane D. Johnson

Using charge self-consistent cluster Korringa-Kohn-Rostoker coherent potential approximation (KKR-CPA) band-structure calculations, the authors have studied the hyperfine fields on both Ni and Fe sites in the NixFe1-x alloys. To elucidate the influence of relativistic effects the hyperfine matrix elements have been calculated nonrelativistically as well as completely relativistically The dependence of the hyperfine fields on the environment of a given site has been studied by performing calculations for various atomic configurations around that site. The results of the work are compared with other theoretical data and with experiment.

On Conformal Scalar Curvature Equations In Rn, Yi Li, Wei-Ming Ni

Yi Li

No abstract provided.

Incorporation Of A Product Of Mevalonic Acid Metabolism Into Proteins Of Chinese Hamster Ovary Nuclei, Michael Sinensky, L. A. Beck, T. Hosick

Michael Sinensky

We have examined the nuclear localization of isoprenylated proteins in CHO-K1 cells labeled with [14C]mevalonate. Nuclear proteins of 68, 70, and 74 kD, posttranslationally modified by an isoprenoid, are also components of a nuclear matrix-intermediate filament preparation from CHO cells. Furthermore, the 68-, 70-, and 74-kD isoprenylated polypeptides are immunoprecipitated from cell extracts with two different anti-lamin antisera. Based on exact two-dimensional comigration with lamin B, both from rat liver lamin and CHO nuclear matrix-intermediate filament preparations, and its immunoprecipitation with anti-lamin antisera, we conclude that the 68-kD isoprenylated protein found in nuclei from [14C]mevalonate-labeled CHO cells is lamin B. …

Vibrational Frequencies And Intensities Of H‐Bonded And Li‐Bonded Complexes. H3n⋅⋅Hcl And H3n⋅⋅Licl, M. M. Szczesniak, I. J. Kurnig, Steve Scheiner

Steve Scheiner

The geometries, energetics, and vibrational spectra are calculated for the two complexes at the SCF and correlated MP2 levels using the 6‐31G∗∗ basis set, augmented by a second set of d functions on Cl. While correlation represents an important factor in the binding of H₃ N⋅⋅HCl, it contributes little to the stronger Li bond. Unlike the HCl stretch ν_s which decreases substantially in frequency and is greatly intensified in H₃ N⋅⋅HCl, the frequency of the LiCl stretch undergoes an increase and little change is noted in its intensity, conforming to prior spectral measurements. The intensities of the …

Optimized Spectroscopic Signal Estimates Using Integration And Matched Filters, Stephen E. Bialkowski

Stephen E. Bialkowski

This paper examines theories of signal processing as applied to peak magnitude estimation in absorption and emission spectroscopy. Signals obtained from Fourier transform, fixed wavelength, and scanning dispersive instruments are modeled in terms of the time required to obtain a spectrum. The differences between these techniques and the signal processing procedures that should be used for each technique are characterized for a Lorentzian spectral feature. Including the time required to scan over a range of optical frequencies results in optimal signal processing procedures that are different from those previously supposed. In particular, it is found that the optimal matched filter …

Bubbles Without Cores, T. C. Shen

T. -C. Shen

The decay of a false vacuum in a theory without a true vacuum is studied. Using variational arguments, we find that for a class of potentials of the type aφⁱ+bφⁱ (a>0, b<0 and i2φ²—ηφ³+ λφ⁴ is presented to discuss the transition from a thin-wall bubble to a thick-walled one. The validity conditions of using these solutions to describe the false vacuum decay within the framework of the semiclassical approximation are discussed.

Gauge-Invariance And Quantization, Br Holstein

Barry R Holstein

Quantizing theories such as quantum electrodynamics that contain a gauge invariance are discussed via a simple pedagogical example. Canonical and path integral quantization methods are compared.

On A General Class Of Multivariate Linear Smoothing Operators, Tian-Xiao He

Tian-Xiao He

No abstract provided.