Library

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    ISSN: 1432-2234
    Keywords: Key words: Polarized basis sets ; Relativistic effects ; Douglas-Kroll approximation ; Ionization potentials of group Ia and IIa metals
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract. The technique previously developed for the generation of the so-called first-order polarized basis sets for accurate non-relativistic calculations of molecular electric properties is used to obtain similar basis sets suitable for calculations in the Douglas-Kroll no-pair approximation. The corresponding (relativistic) basis sets are constructed for atoms of groups Ia and IIa of the Periodic Table and tested in calculations of atomic and ionic polarizabilities. Also the first ionization potential of the group Ia and the first and second ionization potential of the group IIa metals have been evaluated to provide additional qualification of the generated basis sets. The present results are compared with earlier non-relativistic and quasirelativistic data and the role of the relativistic effect is discussed.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    ISSN: 0040-5744
    Keywords: Key words: Polarized basis sets ; Electric dipole polarizabilities of Zn ; Cd ; Hg ; and their positive ions ; Electron correlation effects on atomic properties ; Relativistic effects on atomic properties
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary. The first-order polarized basis sets are generated for Zn, Cd, and Hg and their performance is tested in high-level-correlated calculations of electric dipole polarizabilities of these atoms. The present results calculated at the level of the non-relativistic CCSD(T) approximation with 12 explicitly correlated electrons are: 40.4 a.u. for Zn, 56.3 a.u. for Cd, and 58.0 a.u. for Hg. Upon including the relativistic and electron correlation–relativistic corrections within the quasirelativistic scheme based on the mass–velocity and Darwin terms these values are reduced to 37.9 a.u., 47.6 and 31.8 a.u., respectively. The derived polarized basis sets have been also used for the evaluation of the dipole polarizability of singly and doubly positive ions of the group IIb elements and are recommended for calculations of interaction energies and interaction-induced electric properties in both neutral and charged systems.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 3
    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
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 4
    ISSN: 0040-5744
    Keywords: Key words: Polarized basis sets ; Relativistic effects ; Douglas ; Kroll no-pair approximation ; Dipole polarizabilities of Zn ; Cd ; Hg ; Dipole moments of CuH ; AgH ; and AuH ; Polarizabilities of atomic ions: Cu+ ; Ag+ ; Zn2+ ; Cd2+ ; Hg2+
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary.  The technique developed earlier for the generation of the so-called first-order polarized basis sets for accurate non-relativistic calculations of molecular electric properties is used to obtain similar basis sets suitable for calculations in the Douglas–Kroll no-pair approximation. The corresponding (relativistic) basis sets are devised for atoms of the Groups Ib and IIb of the periodic table and tested in calculations of atomic polarizabilities and dipole moments of the coinage metal hydrides. Excellent performance of these basis sets has been found in the case of molecular calculations.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 5
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 68 (1998), S. 159-174 
    ISSN: 0020-7608
    Keywords: relativistic quantum chemistry ; relativistic connections to expectation valves ; two/one-component methods in relativity ; perturbation methods in relativity ; Douglas-Kroll approximation ; mass-velocity+Darwin approximation ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The effect of the so-called picture change on expectation values of one-electron operators in approximate two(one)-component relativistic theories is discussed. This effect is expected to be particularly large for operators which assume large values in the vicinity of heavy nuclei. The numerical results illustrating the picture change effect on electric field gradients at nuclei have been obtained in the spin-free Pauli and Douglas-Kroll approximations. It has been found that the picture change effect lowers the electric field gradient at I in HI by about 1 a.u. Very large picture change effect (-8 a.u.) has been calculated for HAt. It is concluded that in accurate calculations of expectation values of operators involving high inverse powers of the electron-nucleus distance the picture change, which accompanies the transformation of the Dirac (Dirac-Coulomb) equation to approximate two(one)-component relativistic Hamiltonians, must be taken into account.   © 1998 John Wiley & Sons, Inc. Int J Quant Chem 68: 159-174, 1998
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 6
    ISSN: 0020-7608
    Keywords: relativistic Hamiltonians ; two-component methods in relativity ; perturbation methods in relativity ; Douglas-Kroll approximation ; regular approximations in relativity ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A series of nonsingular two-component relativistic Hamiltonians is derived from the Dirac Hamiltonian by first performing the free-particle Foldy-Wouthuysen transformation and then a block-diagonalizing transformation. The latter is defined in terms of operators which can be determined iteratively through arbitrary order in α, leading to transformed Hamiltonians with the two-component block accurate through α2k, k=1, 2, 3,… . These Hamiltonians give relativistic energies which differ from Dirac's energies only in terms higher than α2k. Their relation to other nonsingular methods of relativistic quantum chemistry (the Douglas-Kroll method, the regular Hamiltonian schemes) is discussed. By removing the spin-dependent operators, the derived Hamiltonians can be written in spin-free one-component form. The computational effort involved is essentially the same as in the case of the Douglas-Kroll scheme and amounts to relatively easy modification of the core Hamiltonian.   © 1997 John Wiley & Sons, Inc. Int J Quant Chem 65: 225-239, 1997
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...