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  • Computational Chemistry and Molecular Modeling  (4)
  • GEOPHYSICS  (4)
  • Calibration  (3)
  • Atomic, Molecular and Optical Physics  (2)
  • 1985-1989  (11)
Collection
Keywords
Publisher
Years
Year
  • 1
    Electronic Resource
    Electronic Resource
    Surface states in deformed and perturbed diatomic crystals (1989)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 36 (1989), S. 553-561 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The electronic properties of a one-dimensional diatomic crystal have been analyzed by using the MO-LCAO method in the tight binding approximation, with mathematical techniques involved in setting up and solving difference equations. The approach gives the exact sets of analytic solutions for both localized and nonlocalized states. The theory of surface states is developed as a characteristic value problem. To illustrate the method the surface states for a semiinfinite crystal which contains a local imperfection at the surface were examined. It appears that this method has advantages over previous methods developed to solve surface problems in crystalline lattices.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560360503
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Approximate solutions of Heisenberg Hamiltonians (1987)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 31 (1987), S. 903-925 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Even when each atom of a 2n-center cluster or molecule only brings one active electron in one atomic orbital, the size of the Heisenberg Hamiltonian matrix increases as C2nn. Simple truncations of this matrix would result in size consistence defects, as evident from the isomorphism between Heisenberg and configuration interaction (CI) matrices. Geometry-dependent Heisenberg Hamiltonians derived from accurate ab initio calculations on the two-center systems have proved to be very efficient for conjugated hydrocarbons and for alkali metals; in order to apply this approach to intermediate size systems (10-20 centers), a rational procedure is proposed consisting of the selection of a truncated set of determinants (of low energy) and a dressing of the truncated Hamiltonian matrix under the perturbation of the other determinants. The second order dressing is analogous to a so-called “shift Bk procedure” or Generalized Degenerate Perturbation theory and is weakly dependent on an E0 parameter. Tests performed on various 8- and 10-atom systems show the accuracy of the procedure. An iterative selection of the truncated basis set and proper choices of the E0 values allow one to obtain the whole lower part of the spectrum. The calculated geometries are satisfactory. Some preliminary applications are reported concerning the C12H14 dodecahexene linear chain, perfectly fitting with previous extrapolations.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560310606
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Tensorial calibration: I. First-order calibration (1988)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 2 (1988), S. 247-263 
    Details
    ISSN: 0886-9383
    Keywords: Calibration ; Tensor ; Multivariate ; PCR ; MLR ; PLS ; Regression ; Multidimensional arrays ; Order ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Many analytical instruments now produce one-, two- or n-dimensional arrays of data that must be used for the analysis of samples. An integrated approach to linear calibration of such instruments is presented from a tensorial point of view. The data produced by these instruments are seen as the components of a first-, second- or nth-order tensor respectively. In this first paper, concepts of linear multivariate calibration are developed in the framework of first-order tensors, and it is shown that the problem of calibration is equivalent to finding the contravariant vector corresponding to the analyte being calibrated. A model of the subspace spanned by the variance in the calibration must be built to compute the contravarian vectors. It is shown that the only difference between methods such as least squares, principal components regression, latent root regression, ridge regression and partial least squres resides in the choice of the model.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cem.1180020404
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  • 4
    Electronic Resource
    Electronic Resource
    Tensorial calibration: II. Second-order calibration (1988)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 2 (1988), S. 265-280 
    Details
    ISSN: 0886-9383
    Keywords: Calibration ; Tensor ; Multivariate ; Order ; Regression ; Generalized rank annihilation ; GRAM ; Multi order ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Tensorial calibration provides a useful approach to calibration in general. For calibration of instruments that produce two-dimensional (second-order) arrays of data per sample, tensoial concepts are as natural a way of solving the calibration problem as vectorial concepts are for the multivariate problem. Similarly, for third- and higher-order data, the tensorial description of calibration is also useful. This paper introduces second-order calibration from a tensorial point of view. Univariate, multivariate and bilinear approaches to calibration are presented. The generalized rank annihilation method (GRAM) is described from the tensorial perspective, and it is shown that GRAM is equivalent to finding a second-order tensorial base that spans both tensors (calibration and unknown) with respective diagonal component matrices. GRAM uses a single calibration sample for multicomponent analysis even in the presence of interference. Second-order bilinear calibration is extended to multiple calibration samples where the effect of collinearities is reduced.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cem.1180020405
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  • 5
    Electronic Resource
    Electronic Resource
    An improved algorithm for the generalized rank annihilation method (1989)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 3 (1989), S. 493-498 
    Details
    ISSN: 0886-9383
    Keywords: Rank annihilation ; Generalized rank annihilation method ; Generalized eigenproblem ; Calibration ; Spectral interferents ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An improved algorithm for the generalized rank annihilation method (GRAM) is presented. GRAM is a method for multicomponent calibration using two-dimensional instruments, such as GC-MS. In this paper an orthonormal base is first computed and used to project the calibration and unknown sample response matrices into a lower-dimensional subspace. The resulting generalized eigenproblem is then solved using the QZ algorithm. The result of these improvements is that GRAM is computationally more stable, particularly in the case where the calibration sample contains chemical constituents not present in the unknown sample and the unknown contains constituents not present in the calibration (the most general case).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cem.1180030306
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  • 6
    Electronic Resource
    Electronic Resource
    Study of a medium-size biological molecular association by means of a pair potential semiempirical approach: β-carboline-lumiflavin (1985)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 6 (1985), S. 441-446 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The molecular association between some substituted β-carbolines and a model flavin, lumiflavin, has been studied by means of a semiempirical approach proposed by Fraga based on a 1/R expansion of atom-atom pair potentials. Only stacked minima have been considered because of their possible biological interest. The calculations characterize 15 different minimum stacked conformations, most of them occurring in the complexes considered. The structural and energetic effects of 1-Me, 6-OH and 7-OH substituents of β-carboline are discussed. An equilibrium conformation involving geometric overlap between the pteridinic portion of flavin and the indole group of β-carboline is predicted to be the most characteristic structure of the complexes. The recognition of this feature can serve to check the effect of substituents and substitution sites of β-carboline in its association complexes.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540060512
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  • 7
    Electronic Resource
    Electronic Resource
    The tautomerism of 1,2,3-triazole, 3(5)-methylpyrazole and their cations (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 10 (1989), S. 426-433 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The annular tautomerism of 1,2,3-triazole and 3(5)-methylpyrazole is discussed by means of a combination of theoretical calculations and experimental (ICR) gas-phase basicities and acidities. In the gas phase 1,2,3-triazole exists as the 2H-tautomer, whereas both tautomers of 3(5)-methylpyrazole are of similar energy. The solvent effects on these prototropic equilibria are discussed taking into account solvent properties as polarity/polarizability, acidity, and basicity. In nonhydrogen bonding solvents, the difference in dipole moments between both tautomers plays a role that has usually been underestimated.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540100318
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  • 8
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    Gravitational model improvement at the Goddard Space Flight Center (1989)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: Major new computations of terrestrial gravitational field models were performed by the Geodynamics Branch of Goddard Space Flight Center (GSFC). This development has incorporated the present state of the art results in satellite geodesy and have relied upon a more consistent set of reference constants than was heretofore utilized in GSFC's GEM models. The solutions are complete in spherical harmonic coefficients out to degree 50 for the gravity field parameters. These models include adjustment for a subset of 66 ocean tidal coefficients for the long wavelength components of 12 major ocean tides. This tidal adjustment was made in the presence of 550 other fixed ocean tidal terms representing 32 major and minor ocean tides and the Wahr frequency dependent solid earth tidal model. In addition 5-day averaged values for Earth rotation and polar motion were derived for the time period of 1980 onward. Two types of models were computed. These are satellite only models relying exclusively on tracking data and combination models which have incorporated satellite altimetry and surface gravity data. The satellite observational data base consists of over 1100 orbital arcs of data on 31 satellites. A large percentage of these observations were provided by third generation laser stations (less than 5 cm). A calibration of the model accuracy of the GEM-T2 satellite only solution indicated that it was a significant improvement over previous models based solely upon tracking data. The rms geoid error for this field is 110 cm to degree and order 36. This is a major advancement over GEM-T1 whose errors were estimated to be 160 cm. An error propagation using the covariances of the GEM-T2 model for the TOPEX radial orbit component indicates that the rms radial errors are expected to be 12 cm. The combination solution, PGS-3337, is a preliminary effort leading to the development of GEM-T3. PGS-3337 has incorporated global sets of surface gravity data and the Seasat altimetry to produce a model complete to (50,50). A solution for the dynamic ocean topography to degree and order 10 was included as part of this adjustment.
    Keywords: GEOPHYSICS
    Type: Ohio State Univ., Progress in the Determination of the Earth's Gravity Field; p 3-7
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 9
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    Radial deformation of the earth by oceanic tidal loading (1989)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A high-degree spherical harmonic series is used to compute the radial deformation of the Earth by oceanic tidal loading. By exploiting fast numerical transforms, this approach is found to be much more efficient, but no less accurate, than the traditional Green's function approach. The method is used to derive an atlas of load tide maps for 10 constitutents of the NSWC ocean tide model.
    Keywords: GEOPHYSICS
    Type: NASA-TM-100743 , REPT-89-154 , NAS 1.15:100743
    Format: application/pdf
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  • 10
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    An improved model of the Earth's gravitational field: GEM-T1 (1987)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Goddard Earth Model T1 (GEM-T1), which was developed from an analysis of direct satellite tracking observations, is the first in a new series of such models. GEM-T1 is complete to degree and order 36. It was developed using consistent reference parameters and extensive earth and ocean tidal models. It was simultaneously solved for gravitational and tidal terms, earth orientation parameters, and the orbital parameters of 580 individual satellite arcs. The solution used only satellite tracking data acquired on 17 different satellites and is predominantly based upon the precise laser data taken by third generation systems. In all, 800,000 observations were used. A major improvement in field accuracy was obtained. For marine geodetic applications, long wavelength geoidal modeling is twice as good as in earlier satellite-only GEM models. Orbit determination accuracy has also been substantially advanced over a wide range of satellites that have been tested.
    Keywords: GEOPHYSICS
    Type: NASA-TM-4019 , REPT-87B0451 , NAS 1.15:4019
    Format: application/pdf
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