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  • 1
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 97 (1992), S. 9216-9221 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Gradient corrected density functionals yield average errors in the ionization potentials of 0.3–0.8 eV. The average errors in the dissociation energies of the diatomic cations are similar to the corresponding errors of the neutral molecules, i.e., 0.2–0.6 eV. The wrong behavior of the potential curves of the dimer cations at large distances calculated with these functionals does not affect the accuracy of De.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 94 (1991), S. 1360-1366 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Quasirelativistic and nonrelativistic 10-valence-electron pseudopotentials for Ca, Sr, and Ba are presented. Results of calculations with 6s6p5d basis sets for MH, MH+, and MH2 are compared with all-electron and 2-valence-electron pseudopotential calculations with and without core-polarization potentials. The 10-valence-electron pseudopotential approach agrees well with all-electron calculations. It circumvents problems for the 2-valence-electron pseudopotentials arising from an incomplete separation of valence and subvalence shells in polar molecular systems due to strongly contracted occupied (n−1)-d orbitals. All higher-level calculations show SrH2 and BaH2 to be bent with angles of ∼140° and 120°, respectively, while CaH2 is linear with a flat potential-energy surface for the bending motion. The use of a core-polarization potential together with the 2-valence-electron pseudopotential approach allows an investigation of the relative importance of core-polarization vs direct d-orbital bonding participation as reasons for the bent structures. The calculations strongly suggest that both contribute to the bending in SrH2 and BaH2. Even at the Hartree–Fock level of theory 10-valence-electron pseudopotential calculations given reasonable angles when the potential-energy surface is not exceedingly flat, and only moderately contracted basis sets including both compact d functions and diffuse p functions are used. The effect of core-valence correlation and the importance of f functions also are discussed.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 100 (1994), S. 7535-7542 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We present nonrelativistic and quasirelativistic energy-adjusted pseudopotentials, the latter augmented by spin–orbit operators, as well as optimized (12s11p10d8f)/ [8s7p6d4f]-Gaussian-type orbitals (GTO) valence basis sets for the actinide elements actinium through lawrencium. Atomic excitation and ionization energies obtained by the use of these pseudopotentials and basis sets in self-consistent field (SCF) calculations differ by less than 0.2 eV from corresponding finite-difference all-electron results. Large-scale multiconfiguration self-consistent field (MCSCF), multireference configuration interaction (MRCI), and multireference averaged coupled-pair functional (MRACPF) calculations for thorium and thorium monoxide yield results in satisfactory agreement with available experimental data. Preliminary results from spin–orbit configuration interaction calculations for the low-lying electronic states of thorium monoxide are also reported.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Inorganic chemistry 29 (1990), S. 860-868 
    ISSN: 1520-510X
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-1904
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Natural Sciences in General
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Monatshefte für Chemie 102 (1971), S. 1709-1717 
    ISSN: 1434-4475
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Das Konzept basiert darauf, die Wellenfunktionen zur Berechnung von Übergangselementen und Erwartungswerten (ohne So) nicht der Energievariation zu entnehmen, sondern aus bestimmten Ungleichungen für die gesuchten Größen, die auch als Variationscrechnungen brauchbar sind, da die aus der Energievariation erhaltenen Näherungslösungen $$\widetilde\psi $$ in der Regel in den Raumbereichen die wirklichen Wellenfunktionen ψ am besten approximieren, die für bestimmte Erwartungswerte und Übergangselemente weniger von Bedeutung sind. Es werden weitere Abschätzungen für $$\left\langle {{\psi \mathord{\left/ {\vphantom {\psi {\widetilde\psi }}} \right. \kern-\nulldelimiterspace} {\widetilde\psi }}} \right\rangle $$ angegeben.
    Notes: Abstract The concept is based on the derivation of the wave functions for calculating transition elements and expectancy values (without So) from specific inequalities for the variables sought instead of from the energy variation. The inequalities can also be used as a calculus of variations, as the approximate solutions $$\widetilde\psi $$ obtained from the energy variation are generally the best approximations in the spatial regions to the actual wave functions, which are of less significance for specific expectancy values and transition elements. Further estimates of $$\left\langle {{\psi \mathord{\left/ {\vphantom {\psi {\widetilde\psi }}} \right. \kern-\nulldelimiterspace} {\widetilde\psi }}} \right\rangle $$ are given.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1432-2234
    Keywords: Key words: Collision complexes ; Pseudopotential method ; Potential curves
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract. Adiabatic potential curves for the ground state and several low-lying excited states of the barium atom interacting with Ne, Ar, Kr and Xe have been obtained from valence ab initio configuration-interaction calculations. Atomic cores are replaced by scalar-relativistic l-dependent pseudopotentials, while core-polarization potentials are used for describing correlation contributions of the rare-gas atoms and the Ba2+ cores. Implications of the resulting potential curves for the interpretation of experimental data are discussed, together with first applications of the curves for calculating absorption profiles of the (6s 2)1S→(6p)1P Ba transition.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical chemistry accounts 77 (1990), S. 123-141 
    ISSN: 1432-2234
    Keywords: Pseudopotentials ; Spin-orbit operator ; Transition metals
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Nonrelativistic and quasirelativisticab initio pseudopotentials substituting the M(Z−28)+-core orbitals of the second row transition elements and the M(Z−60)+-core orbitals of the third row transition elements, respectively, and optimized (8s7p6d)/[6s5p3d]-GTO valence basis sets for use in molecular calculations have been generated. Additionally, corresponding spin-orbit operators have also been derived. Atomic excitation and ionization energies from numerical HF as well as from SCF pseudopotential calculations using the derived basis sets differ in most cases by less than 0.1 eV from corresponding numerical all-electron results. Spin-orbit splittings for lowlying states are in reasonable agreement with corresponding all-electron Dirac-Fock (DF) results.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1432-2234
    Keywords: Pseudopotentials ; Transition metals
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Recently published nonrelativistic and quasirelativistic energy-adjustedab initio pseudopotentials representing the M(Z−28)+ cores of the second row transition metal atoms and the M(Z−60)+ cores of the third row transition metal atoms have been tested in SCF, CI(SD) and CEPA1 calculations of the spectroscopic constants (R e ,D e , and ω e ) of the ground states of the neutral and singly charged silver and gold dimers, and in state averaged CASSCF and multi-reference CI(SD) calculations of the spectroscopic constants (R e ,D e , ω e , μ e , ∂μ/∂R). Comparison is made with experimental and reliable theoretical data where available; in the case of the hydrides, additional calculations with pseudopotentials published by other groups have been made for comparison.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical chemistry accounts 85 (1993), S. 441-450 
    ISSN: 1432-2234
    Keywords: Lanthanoid elements ; Pseudopotentials ; Ligand field model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Improved energy-adjusted quasirelativistic pseudopotentials for lanthanoid atoms with fixed valency are presented and tested in molecular calculations for CeO, CeF, EuO, GdO, YbO, and YbF. The pseudopotential calculations treat the lanthanoid 4f shell as part of the core and yield accurate estimates for average bond lengths, vibrational frequencies and dissociation energies of all states belonging to a superconfiguration. Information for each individual state of the considered superconfiguration may be obtained from subsequent ligand field model calculations. The results of this combined pseudo-potential and ligand field approach (PPLFT) are compared to more accurate calculations with ab initio pseudopotentials that include the lanthanoid 4f orbitals explicitly in the valence shell and to available experimental data.
    Type of Medium: Electronic Resource
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