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  • Polarization functions, exponent optimization of ∼  (2)
  • Quadratic configuration interaction  (2)
  • correlation corrections  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Polarization functions for gaussian basis sets for the first row atoms (1977)
    Springer
    Theoretical chemistry accounts 45 (1977), S. 205-213 
    Details
    ISSN: 1432-2234
    Keywords: Polarization functions, exponent optimization of ∼
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Exponent optimization was performed for a single set ofd-type Gaussians on the first row atoms C, N, and O in fifteen small molecules. The hydrogenp-exponents were kept at the fixed value of 1.0. For the underlying valence shell basis sets, Dunning's double zeta basis sets were used. Standard exponents of polarization functions are suggested for the most common valence states of the C, N, and O atoms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02401401
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Polarized basis sets for high-level-correlated calculations of molecular electric properties (1996)
    Springer
    Theoretical chemistry accounts 93 (1996), S. 101-129 
    Details
    ISSN: 1432-2234
    Keywords: Polarized basis sets ; Dipole polarizabilities of Cu, Ag, and Au ; Dipole polarizabilities of Cu+, Ag+, and Au+ ; Relativistic effects on atomic electric properties ; Electron correlation effects on atomic electric properties ; Relativistic ; correlation corrections ; SA CCSD(T) method
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The first-order polarized basis sets PolMe are generated for elements (Me=Cu, Ag, Au) of group Ib of the periodic table by using the basis set polarization method developed in earlier papers. The performance of these basis sets is extensively tested in calculations of atomic dipole polarizabilities with particular attention given to the evaluation of the electron correlation and relativistic contributions. The extension by theg-type polarization functions (PolMe-g sets) is devised for use in accurate calculations of atomic and molecular electric properties. The (negative) electron correlation contribution to dipole polarizabilities of all elements of group Ib, as calculated at the level of the spin adapted coupled cluster method with single and double excitations and non-iterative corrections for the contribution of the T3 clusters (SA CCSD(T)), remains at the same level relative to the ROHF data. The pure relativistic correction to the ROHF results, evaluated within the quasirelativistic approximation involving the mass-velocity and Darwin corrections, is negative and rapidly increases with increase of the nuclear charge. Its large negative value is, for heavier systems, partly compensated by a positive contribution from the mixed relativistic-correlation terms. Our relativistically corrected SA CCSD(T) calculations predict the following values of the dipole polarizability in the coinage metal series: 46, 51, and 29 a.u., for Cu, Ag, and Au. The present results for Cu and Ag agree well with recent pseudopotential calculations by Schwerdtfeger and Bowmaker. However, for Au our result is by about 6 a.u. lower than that obtained by using 19-electron relativistic potentials. Several possible reasons for this discrepancy are discussed. The PolMe and PolMe-g basis sets are also used to calculate electric dipole polarizabilities of the singly positive ions of group Ib elements. The results obtained in the quasirelativistic CCSD(T) approximation are 6.6, 9.2, and 11.8 a.u. for Cu+, Ag+, and Au+, respectively. These values follow the pattern expected for the series of ions whose polarizability is dominated by the next-to-valenced shell.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01113551
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Polarization functions for gaussian basis sets for the first row atoms (1977)
    Springer
    Theoretical chemistry accounts 45 (1977), S. 205-213 
    Details
    ISSN: 1432-2234
    Keywords: Polarization functions, exponent optimization of ∼
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Exponent optimization was performed for a single set ofd-type Gaussians on the first row atoms C, N, and O in fifteen small molecules. The hydrogenp-exponents were kept at the fixed value of 1.0. For the underlying valence shell basis sets, Dunning's double zeta basis sets were used. Standard exponents of polarization functions are suggested for the most common valence states of the C, N, and O atoms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00552682
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Accurate electrical and spectroscopic properties ofX 1Σ+ BeO from coupled-cluster methods (1995)
    Springer
    Theoretical chemistry accounts 90 (1995), S. 341-355 
    Details
    ISSN: 1432-2234
    Keywords: BeO molecule ; Coupled-cluster calculations ; Quadratic configuration interaction ; Spectroscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary This paper reports a series of coupled-cluster (CC) calculations through CCSDT on the theoretically challenging ground state of the BeO molecule. Along with CC methods, quadratic configuration interaction (QCI) approximations to CC theory have been used (QCISD and QCISD(T)), which show several dramatic failings. Equilibrium electrical properties (μ, α xx , and α zz ) and basic spectroscopic properties (r e, θe,D e, and infrared intensity (I)) have been computed. Basis set and electron correlation effects are analyzed in order to arrive at accurate values of the dipole moment and polarizability, which are not known experimentally. For the dipole moment, we obtain a value of 6.25 D, with an uncertainty of about 0.1 D. For α xx and α zz , we suggest respective values of 32 and 36 atomic units (a.u.) and error bars of about 1 and 2 a.u. With extended basis sets, the spectroscopic propertiesr e, θe, andD e are reproduced to high accuracy, which is the first time this has been achieved for this species byab initio methods. At the highest calculation levels,I is predicted to be very small. AlthoughI has not been measured, some support for this prediction comes from a recent infrared study of BeO-rare gas complexes. The QCI methods are shown to be much more sensitive to basis set, and even with large basis sets yield values of α zz andI which differ from CC results by an order of magnitude and three orders of magnitude, respectively. These differences doubtless arise from the importance of single excitations (T 1) for this molecule, as several terms involvingT 1 are neglected in the QCISD approximation compared with CCSD. We also report CC calculations with Brueckner orbitals, which yield results similar to those obtained with restricted Hartree-Fock orbitals.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01113541
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Accurate electrical and spectroscopic properties of X1Σ+ BeO from coupled-cluster methods (1995)
    Springer
    Theoretica chimica acta 90 (1995), S. 341-355 
    Details
    ISSN: 0040-5744
    Keywords: Key words: BeO molecule ; Coupled-cluster calculations ; Quadratic configuration interaction ; Spectroscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary.  This paper reports a series of coupled-cluster (CC) calculations through CCSDT on the theoretically challenging ground state of the BeO molecule. Along with CC methods, quadratic configuration interaction (QCI) approximations to CC theory have been used (QCISD and QCISD(T)), which show several dramatic failings. Equilibrium electrical properties (μ, α xx , and α zz ) and basic spectroscopic properties (r e, ωe, D e, and infrared intensity (I)) have been computed. Basis set and electron correlation effects are analyzed in order to arrive at accurate values of the dipole moment and polarizability, which are not known experimentally. For the dipole moment, we obtain a value of 6.25 D, with an uncertainty of about 0.1 D. For α xx and α zz , we suggest respective values of 32 and 36 atomic units (a.u.) and error bars of about 1 and 2 a.u. With extended basis sets, the spectroscopic properties r e, ωe, and D e are reproduced to high accuracy, which is the first time this has been achieved for this species by ab initio methods. At the highest calculation levels, I is predicted to be very small. Although I has not been measured, some support for this prediction comes from a recent infrared study of BeO–rare gas complexes. The QCI methods are shown to be much more sensitive to basis set, and even with large basis sets yield values of α zz and I which differ from CC results by an order of magnitude and three orders of magnitude, respectively. These differences doubtless arise from the importance of single excitations (T 1) for this molecule, as several terms involving T 1 are neglected in the QCISD approximation compared with CCSD. We also report CC calculations with Brueckner orbitals, which yield results similar to those obtained with restricted Hartree–Fock orbitals.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01113541
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Polarized basis sets for high-level-correlated calculations of molecular electric properties VII. Elements of the group Ib: Cu, Ag, Au (1996)
    Springer
    Theoretica chimica acta 93 (1996), S. 101-129 
    Details
    ISSN: 0040-5744
    Keywords: Key words: Polarized basis sets ; Dipole polarizabilities of Cu ; Ag ; and Au ; Dipole polarizabilities of Cu+ ; Ag+ ; and Au+ ; Relativistic effects on atomic electric properties ; Electron correlation effects on atomic electric properties ; Relativistic ; correlation corrections ; SA CCSD(T) method
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary.  The first-order polarized basis sets PolMe are generated for elements (Me=Cu, Ag, Au) of group Ib of the periodic table by using the basis set polarization method developed in earlier papers. The performance of these basis sets is extensively tested in calculations of atomic dipole polarizabilities with particular attention given to the evaluation of the electron correlation and relativistic contributions. The extension by the g-type polarization functions (PolMe-g sets) is devised for use in accurate calculations of atomic and molecular electric properties. The (negative) electron correlation contribution to dipole polarizabilities of all elements of group Ib, as calculated at the level of the spin adapted coupled cluster method with single and double excitations and non-iterative corrections for the contribution of the T3 clusters (SA CCSD(T)), remains at the same level relative to the ROHF data. The pure relativistic correction to the ROHF results, evaluated within the quasirelativistic approximation involving the mass–velocity and Darwin corrections, is negative and rapidly increases with increase of the nuclear charge. Its large negative value is, for heavier systems, partly compensated by a positive contribution from the mixed relativistic–correlation terms. Our relativistically corrected SA CCSD(T) calculations predict the following values of the dipole polarizability in the coinage metal series: 46, 51, and 29 a.u., for Cu, Ag, and Au. The present results for Cu and Ag agree well with recent pseudopotential calculations by Schwerdtfeger and Bowmaker. However, for Au our result is by about 6 a.u. lower than that obtained by using 19-electron relativistic potentials. Several possible reasons for this discrepancy are discussed. The PolMe and PolMe-g basis sets are also used to calculate electric dipole polarizabilities of the singly positive ions of group Ib elements. The results obtained in the quasirelativistic CCSD(T) approximation are 6.6, 9.2, and 11.8 a.u. for Cu+, Ag+, and Au+, respectively. These values follow the pattern expected for the series of ions whose polarizability is dominated by the next-to-valence d shell.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01113551
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
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