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  • AIP Publishing  (15)
  • Cremer, Dieter  (15)
  • Filatov, Michael  (15)
Medientyp
Verlag/Herausgeber
  • AIP Publishing  (15)
Person/Organisation
  • Cremer, Dieter  (15)
  • Filatov, Michael  (15)
  • Zou, Wenli  (6)
Sprache
Erscheinungszeitraum
  • 1
    Online-Ressource
    Online-Ressource
    Relativistically corrected nuclear magnetic resonance chemical shifts calculated with the normalized elimination of the small component using an effective potential-NMR chemical shifts of molybdenum and tungsten
    AIP Publishing ; 2003
    In:  The Journal of Chemical Physics Vol. 119, No. 2 ( 2003-07-08), p. 701-712
    Details
    In: The Journal of Chemical Physics, AIP Publishing, Vol. 119, No. 2 ( 2003-07-08), p. 701-712
    Kurzfassung: A new method for relativistically corrected nuclear magnetic resonance (NMR) chemical shifts is developed by combining the individual gauge for the localized orbital approach for density functional theory with the normalized elimination of a small component using an effective potential. The new method is used for the calculation of the NMR chemical shifts of Mo95 and W183 in various molybdenum and tungsten compounds. It is shown that quasirelativistic corrections lead to an average improvement of calculated NMR chemical shift values by 300 and 120 ppm in the case of Mo95 and W183, respectively, which is mainly due to improvements in the paramagnetic contributions. The relationship between electronic structure of a molecule and the relativistic paramagnetic corrections is discussed. Relativistic effects for the diamagnetic part of the magnetic shielding caused by a relativistic contraction of the s,p orbitals in the core region concern only the shielding values, however, have little consequence for the shift values because of the large independence from electronic structure and a cancellation of these effects in the shift values. It is shown that the relativistic corrections can be improved by level shift operators and a B3LYP hybrid functional, for which Hartree–Fock exchange is reduced to 15%.
    Materialart: Online-Ressource
    ISSN: 0021-9606 , 1089-7690
    URL: Article
    DOI: 10.1063/1.1580091
    Sprache: Englisch
    Verlag: AIP Publishing
    Publikationsdatum: 2003
    ZDB Id: 3113-6
    ZDB Id: 1473050-9
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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    Online-Ressource
    Open Access Wunsch
    Verfügbarkeit (elektronisch / print)
    BTU Cottbus
    Wissenschaftspark Albert Einstein
    TH Wildau
  • 2
    Online-Ressource
    Online-Ressource
    Relativistically corrected electric field gradients calculated with the normalized elimination of the small component formalism
    AIP Publishing ; 2012
    In:  The Journal of Chemical Physics Vol. 137, No. 5 ( 2012-08-07)
    Details
    In: The Journal of Chemical Physics, AIP Publishing, Vol. 137, No. 5 ( 2012-08-07)
    Kurzfassung: Based on the analytic derivatives formalism for the spin-free normalized elimination of the small component method, a new computational scheme for the calculation of the electric field gradient at the atomic nuclei was developed and presented. The new computational scheme was tested by the calculation of the electric field gradient at the mercury nucleus in a series of Hg-containing inorganic and organometallic compounds. The benchmark calculations demonstrate that the new formalism is capable of reproducing experimental and theoretical reference data with high accuracy. The method developed can be routinely applied to the calculation of large and very large molecules and holds considerable promise for the interpretation of the experimental data of biologically relevant compounds containing heavy elements.
    Materialart: Online-Ressource
    ISSN: 0021-9606 , 1089-7690
    URL: Article
    DOI: 10.1063/1.4742175
    Sprache: Englisch
    Verlag: AIP Publishing
    Publikationsdatum: 2012
    ZDB Id: 3113-6
    ZDB Id: 1473050-9
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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    Online-Ressource
    Open Access Wunsch
    Verfügbarkeit (elektronisch / print)
    BTU Cottbus
    Wissenschaftspark Albert Einstein
    TH Wildau
  • 3
    Online-Ressource
    Online-Ressource
    Relativistically corrected hyperfine structure constants calculated with the regular approximation applied to correlation corrected ab initio theory
    AIP Publishing ; 2004
    In:  The Journal of Chemical Physics Vol. 121, No. 12 ( 2004-09-22), p. 5618-5622
    Details
    In: The Journal of Chemical Physics, AIP Publishing, Vol. 121, No. 12 ( 2004-09-22), p. 5618-5622
    Kurzfassung: The infinite-order regular approximation (IORA) and IORA with modified metric (IORAmm) is used to develop an algorithm for calculating relativistically corrected isotropic hyperfine structure (HFS) constants. The new method is applied to the calculation of alkali atoms Li–Fr, coinage metal atoms Cu, Ag, and Au, the Hg+ radical ion, and the mercury containing radicals HgH, HgCH3, HgCN, and HgF. By stepwise improvement of the level of theory from Hartree–Fock to second-order Møller–Plesset theory and to quadratic configuration interaction theory with single and double excitations, isotropic HFS constants of high accuracy were obtained for atoms and for molecular radicals. The importance of relativistic corrections is demonstrated.
    Materialart: Online-Ressource
    ISSN: 0021-9606 , 1089-7690
    URL: Article
    DOI: 10.1063/1.1785772
    Sprache: Englisch
    Verlag: AIP Publishing
    Publikationsdatum: 2004
    ZDB Id: 3113-6
    ZDB Id: 1473050-9
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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    Online-Ressource
    Open Access Wunsch
    Verfügbarkeit (elektronisch / print)
    BTU Cottbus
    Wissenschaftspark Albert Einstein
    TH Wildau
  • 4
    Online-Ressource
    Online-Ressource
    Connection between the regular approximation and the normalized elimination of the small component in relativistic quantum theory
    AIP Publishing ; 2005
    In:  The Journal of Chemical Physics Vol. 122, No. 6 ( 2005-02-08)
    Details
    In: The Journal of Chemical Physics, AIP Publishing, Vol. 122, No. 6 ( 2005-02-08)
    Kurzfassung: The regular approximation to the normalized elimination of the small component (NESC) in the modified Dirac equation has been developed and presented in matrix form. The matrix form of the infinite-order regular approximation (IORA) expressions, obtained in [Filatov and Cremer, J. Chem. Phys. 118, 6741 (2003)] using the resolution of the identity, is the exact matrix representation and corresponds to the zeroth-order regular approximation to NESC (NESC-ZORA). Because IORA (=NESC-ZORA) is a variationally stable method, it was used as a suitable starting point for the development of the second-order regular approximation to NESC (NESC-SORA). As shown for hydrogenlike ions, NESC-SORA energies are closer to the exact Dirac energies than the energies from the fifth-order Douglas–Kroll approximation, which is much more computationally demanding than NESC-SORA. For the application of IORA (=NESC-ZORA) and NESC-SORA to many-electron systems, the number of the two-electron integrals that need to be evaluated (identical to the number of the two-electron integrals of a full Dirac–Hartree–Fock calculation) was drastically reduced by using the resolution of the identity technique. An approximation was derived, which requires only the two-electron integrals of a nonrelativistic calculation. The accuracy of this approach was demonstrated for heliumlike ions. The total energy based on the approximate integrals deviates from the energy calculated with the exact integrals by less than 5×10−9hartree units. NESC-ZORA and NESC-SORA can easily be implemented in any nonrelativistic quantum chemical program. Their application is comparable in cost with that of nonrelativistic methods. The methods can be run with density functional theory and any wave function method. NESC-SORA has the advantage that it does not imply a picture change.
    Materialart: Online-Ressource
    ISSN: 0021-9606 , 1089-7690
    URL: Article
    DOI: 10.1063/1.1844298
    Sprache: Englisch
    Verlag: AIP Publishing
    Publikationsdatum: 2005
    ZDB Id: 3113-6
    ZDB Id: 1473050-9
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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    Online-Ressource
    Open Access Wunsch
    Verfügbarkeit (elektronisch / print)
    BTU Cottbus
    Wissenschaftspark Albert Einstein
    TH Wildau
  • 5
    Online-Ressource
    Online-Ressource
    Analytic energy derivatives for regular approximations of relativistic effects applicable to methods with and without correlation corrections
    AIP Publishing ; 2003
    In:  The Journal of Chemical Physics Vol. 118, No. 15 ( 2003-04-15), p. 6741-6750
    Details
    In: The Journal of Chemical Physics, AIP Publishing, Vol. 118, No. 15 ( 2003-04-15), p. 6741-6750
    Kurzfassung: Analytic expressions are derived for the evaluation of derivatives of the total molecular energy with respect to external parameters (nuclear coordinates, external electric fields, etc.) within the relativistic regular approximation. The presented formalism employs the spectral resolution of the identity avoiding, however, the explicit use of an auxiliary basis set in the calculation of the matrix elements of the regular relativistic Hamiltonian. The final formulas for the total energy and energy derivatives are presented in matrix form suitable for implementation into standard quantum chemical packages. Results of benchmark calculations for gold containing diatomic molecules and for xenone hexafluoride performed at the Hartree–Fock and various correlation corrected levels of theory are presented and discussed.
    Materialart: Online-Ressource
    ISSN: 0021-9606 , 1089-7690
    URL: Article
    DOI: 10.1063/1.1561046
    Sprache: Englisch
    Verlag: AIP Publishing
    Publikationsdatum: 2003
    ZDB Id: 3113-6
    ZDB Id: 1473050-9
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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    Online-Ressource
    Open Access Wunsch
    Verfügbarkeit (elektronisch / print)
    BTU Cottbus
    Wissenschaftspark Albert Einstein
    TH Wildau
  • 6
    Online-Ressource
    Online-Ressource
    Representation of the exact relativistic electronic Hamiltonian within the regular approximation
    AIP Publishing ; 2003
    In:  The Journal of Chemical Physics Vol. 119, No. 22 ( 2003-12-08), p. 11526-11540
    Details
    In: The Journal of Chemical Physics, AIP Publishing, Vol. 119, No. 22 ( 2003-12-08), p. 11526-11540
    Kurzfassung: The exact relativistic Hamiltonian for electronic states is expanded in terms of energy-independent linear operators within the regular approximation. An effective relativistic Hamiltonian has been obtained, which yields in lowest order directly the infinite-order regular approximation (IORA) rather than the zeroth-order regular approximation method. Further perturbational expansion of the exact relativistic electronic energy utilizing the effective Hamiltonian leads to new methods based on ordinary (IORAn) or double [IORAn(2)] perturbation theory (n: order of expansion), which provide improved energies in atomic calculations. Energies calculated with IORA4 and IORA3(2) are accurate up to c−2 0. Furthermore, IORA is improved by using the IORA wave function to calculate the Rayleigh quotient, which, if minimized, leads to the exact relativistic energy. The outstanding performance of this new IORA method coined scaled IORA is documented in atomic and molecular calculations.
    Materialart: Online-Ressource
    ISSN: 0021-9606 , 1089-7690
    URL: Article
    DOI: 10.1063/1.1623473
    Sprache: Englisch
    Verlag: AIP Publishing
    Publikationsdatum: 2003
    ZDB Id: 3113-6
    ZDB Id: 1473050-9
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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    Online-Ressource
    Open Access Wunsch
    Verfügbarkeit (elektronisch / print)
    BTU Cottbus
    Wissenschaftspark Albert Einstein
    TH Wildau
  • 7
    Online-Ressource
    Online-Ressource
    Development and application of the analytical energy gradient for the normalized elimination of the small component method
    AIP Publishing ; 2011
    In:  The Journal of Chemical Physics Vol. 134, No. 24 ( 2011-06-28)
    Details
    In: The Journal of Chemical Physics, AIP Publishing, Vol. 134, No. 24 ( 2011-06-28)
    Kurzfassung: The analytical energy gradient of the normalized elimination of the small component (NESC) method is derived for the first time and implemented for the routine calculation of NESC geometries and other first order molecular properties. Essential for the derivation is the correct calculation of the transformation matrix U relating the small component to the pseudolarge component of the wavefunction. The exact form of \documentclass[12pt]{minimal}\begin{document}${\partial \mathbf {U}}/{\partial \lambda }$\end{document}∂U/∂λ is derived and its contribution to the analytical energy gradient is investigated. The influence of a finite nucleus model and that of the picture change is determined. Different ways of speeding up the calculation of the NESC gradient are tested. It is shown that first order properties can routinely be calculated in combination with Hartree-Fock, density functional theory (DFT), coupled cluster theory, or any electron correlation corrected quantum chemical method, provided the NESC Hamiltonian is determined in an efficient, but nevertheless accurate way. The general applicability of the analytical NESC gradient is demonstrated by benchmark calculations for NESC/CCSD (coupled cluster with all single and double excitation) and NESC/DFT involving up to 800 basis functions.
    Materialart: Online-Ressource
    ISSN: 0021-9606 , 1089-7690
    URL: Article
    DOI: 10.1063/1.3603454
    Sprache: Englisch
    Verlag: AIP Publishing
    Publikationsdatum: 2011
    ZDB Id: 3113-6
    ZDB Id: 1473050-9
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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    Online-Ressource
    Open Access Wunsch
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    BTU Cottbus
    Wissenschaftspark Albert Einstein
    TH Wildau
  • 8
    Online-Ressource
    Online-Ressource
    Calculation of indirect nuclear spin–spin coupling constants within the regular approximation for relativistic effects
    AIP Publishing ; 2004
    In:  The Journal of Chemical Physics Vol. 120, No. 24 ( 2004-06-22), p. 11407-11422
    Details
    In: The Journal of Chemical Physics, AIP Publishing, Vol. 120, No. 24 ( 2004-06-22), p. 11407-11422
    Kurzfassung: A new method for calculating the indirect nuclear spin–spin coupling constant within the regular approximation to the exact relativistic Hamiltonian is presented. The method is completely analytic in the sense that it does not employ numeric integration for the evaluation of relativistic corrections to the molecular Hamiltonian. It can be applied at the level of conventional wave function theory or density functional theory. In the latter case, both pure and hybrid density functionals can be used for the calculation of the quasirelativistic spin–spin coupling constants. The new method is used in connection with the infinite-order regular approximation with modified metric (IORAmm) to calculate the spin–spin coupling constants for molecules containing heavy elements. The importance of including exact exchange into the density functional calculations is demonstrated.
    Materialart: Online-Ressource
    ISSN: 0021-9606 , 1089-7690
    URL: Article
    DOI: 10.1063/1.1752876
    Sprache: Englisch
    Verlag: AIP Publishing
    Publikationsdatum: 2004
    ZDB Id: 3113-6
    ZDB Id: 1473050-9
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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    Online-Ressource
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    BTU Cottbus
    Wissenschaftspark Albert Einstein
    TH Wildau
  • 9
    Online-Ressource
    Online-Ressource
    A gauge-independent zeroth-order regular approximation to the exact relativistic Hamiltonian—Formulation and applications
    AIP Publishing ; 2005
    In:  The Journal of Chemical Physics Vol. 122, No. 4 ( 2005-01-22)
    Details
    In: The Journal of Chemical Physics, AIP Publishing, Vol. 122, No. 4 ( 2005-01-22)
    Kurzfassung: A simple modification of the zeroth-order regular approximation (ZORA) in relativistic theory is suggested to suppress its erroneous gauge dependence to a high level of approximation. The method, coined gauge-independent ZORA (ZORA-GI), can be easily installed in any existing nonrelativistic quantum chemical package by programming simple one-electron matrix elements for the quasirelativistic Hamiltonian. Results of benchmark calculations obtained with ZORA-GI at the Hartree-Fock (HF) and second-order Møller-Plesset perturbation theory (MP2) level for dihalogens X2 (X=F,Cl,Br,I,At) are in good agreement with the results of four-component relativistic calculations (HF level) and experimental data (MP2 level). ZORA-GI calculations based on MP2 or coupled-cluster theory with single and double perturbations and a perturbative inclusion of triple excitations [CCSD(T)] lead to accurate atomization energies and molecular geometries for the tetroxides of group VIII elements. With ZORA-GI/CCSD(T), an improved estimate for the atomization energy of hassium (Z=108) tetroxide is obtained.
    Materialart: Online-Ressource
    ISSN: 0021-9606 , 1089-7690
    URL: Article
    DOI: 10.1063/1.1839856
    Sprache: Englisch
    Verlag: AIP Publishing
    Publikationsdatum: 2005
    ZDB Id: 3113-6
    ZDB Id: 1473050-9
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Online-Ressource
    Open Access Wunsch
    Verfügbarkeit (elektronisch / print)
    BTU Cottbus
    Wissenschaftspark Albert Einstein
    TH Wildau
  • 10
    Online-Ressource
    Online-Ressource
    Analytic calculation of second-order electric response properties with the normalized elimination of the small component (NESC) method
    AIP Publishing ; 2012
    In:  The Journal of Chemical Physics Vol. 137, No. 8 ( 2012-08-28)
    Details
    In: The Journal of Chemical Physics, AIP Publishing, Vol. 137, No. 8 ( 2012-08-28)
    Kurzfassung: Analytic second derivatives of the relativistic energy for the calculation of electric response properties are derived utilizing the normalized elimination of the small component (NESC) method. Explicit formulas are given for electric static dipole polarizabilities and infrared intensities by starting at the NESC representation of electric dipole moments. The analytic derivatives are implemented in an existing NESC program and applied to calculate dipole moments, polarizabilities, and the infrared spectra of gold- and mercury-containing molecules as well as some actinide molecules. Comparison with experiment reveals the accuracy of NESC second order electric response properties.
    Materialart: Online-Ressource
    ISSN: 0021-9606 , 1089-7690
    URL: Article
    DOI: 10.1063/1.4747335
    Sprache: Englisch
    Verlag: AIP Publishing
    Publikationsdatum: 2012
    ZDB Id: 3113-6
    ZDB Id: 1473050-9
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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    Online-Ressource
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    BTU Cottbus
    Wissenschaftspark Albert Einstein
    TH Wildau
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