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  • 1
    Electronic Resource
    Electronic Resource
    Estimates of relativistic contributions to molecular properties (1990)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 93 (1990), S. 8122-8132 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: A simple method for the estimation of the relativistic contribution to atomic and molecular properties is proposed. The method assumes that the dominant portion of relativistic contribution to different properties is accounted for by the Cowan–Griffin operator. In contrast to recently investigated variational relativistic and quasirelativistic approaches, the present method is based virtually on the triple-perturbation theory approach and can be easily executed in the framework of the finite-field perturbation schemes. The method proposed in this paper is applied to the evaluation of the relativistic contribution to electric properties of hydrogen halides. This contribution turns out to be completely negligible in the case of HCl. For the HI molecule, the relativistic correction to its dipole moment becomes almost as important as the electron correlation effects. A similar result is also obtained in the case of the dipole moment of AgH. Different possible applications of the present method are discussed. The major advantage of the proposed perturbation approach is a very simple computational structure which permits the calculation of relativistic corrections from any available nonrelativistic wave function.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.459342
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  • 2
    Electronic Resource
    Electronic Resource
    Quadrupole moments of CuH, AgH, and AuH. A study of the electron correlation and relativistic effects (1991)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 95 (1991), S. 8248-8253 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: High-level correlated calculations of the quadrupole moment of the group-Ib hydrides have been carried out with large Gaussian-type-orbital/contracted-Gaussian-type-orbital basis sets. The nonrelativistic results obtained for CuH, AgH, and AuH at the self-consistent-field Hartree–Fock level of approximation and for the origin at the heavy atom are −2.16, −3.17, and −1.94 a.u., respectively. The electron correlation contribution computed by using the coupled-cluster approaches reduces those values to −0.25, −1.14, and −0.18 a.u., respectively. The relativistic corrections have been obtained from the recently developed quasirelativistic method. They have been found to be of increasing importance for the investigated series of hydrides. The final relativistically corrected values of molecular quadrupole moments are found to be small for CuH (+0.05 a.u.) and AgH (−0.36 a.u.) while the corresponding value for AuH is large and positive (+2.00 a.u.).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.461303
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  • 3
    Electronic Resource
    Electronic Resource
    Quasirelativistic studies of molecular electric properties: Dipole moments of the group IVa oxides and sulfides (1993)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 98 (1993), S. 1345-1351 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Dipole moments of SiO, GeO, SnO, PbO, and of the corresponding sulfides are computed by using a variety of high-level correlated methods and polarized basis sets of Gaussian functions. The contribution of relativistic effects has been accounted for by the first-order quasirelativistic approach based on mass-velocity and Darwin terms. The results for sulfides are in good agreement with experiment while for oxides seem to show a progressive deterioration with the increase of the heavy atom nuclear charge. The discrepancies between the calculated and experimental dipole moments for oxides have been carefully analyzed for the PbO molecule in terms of the basis set choice and reliability of the calculated electron correlation and relativistic corrections. The pattern of relativistic corrections computed in the present study is compared with that which follows from recent quasirelativistic and fully relativistic calculations of Dyall. Some complementary calculations of the dipole moment of PbSe and PbTe seem to indicate that both the polarized basis sets and computational methods used in this study should not fail to predict correct values of the dipole moment of PbO and other oxides of the group IVa atoms. The rather unexpected discrepancies have no plausible explanation within the range of methods employed in our study and offer a challenge for more advanced, fully relativistic molecular calculations at the correlated level of approximation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.464301
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  • 4
    Electronic Resource
    Electronic Resource
    A CAS SCF study of reactive interactions between Be(3 P) and H2(1ε g + ) (1992)
    Springer
    Theoretical chemistry accounts 81 (1992), S. 417-424 
    Details
    ISSN: 1432-2234
    Keywords: Be(3 P) ; H2(1ε g + ) ; CAS SCF ; Adiabatic energy surface
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary TheC 2v symmetry section of the Be(3 P)+ H2(1ε g + ) adiabatic energy surface is investigated by using the CAS SCF method. The small active space CAS SCF calculations in the valence approximation are followed by a perturbation treatment of the dynamic, core, and core-valence contributions in the framework of the CASPT2 method. The possibility of the nonradiative chemical deactivation of the lowest triplet state of Be by the insertion mechanism is studied. The structure of the3 B 2 reaction intermediate BeH2 is established. The calculations show that the symmetric dissociation of this intermediate into Be(1 S) and 2H(2 S) does not involve any barrier beyond the endothermicity of the corresponding reaction. The hydrogen abstraction mechanism via a linear configuration is shown to possess the activation barrier of about 25 mH.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01134865
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  • 5
    Electronic Resource
    Electronic Resource
    Medium-size polarized basis sets for high-level-correlated calculations of molecular electric properties (1992)
    Springer
    Theoretical chemistry accounts 83 (1992), S. 351-366 
    Details
    ISSN: 1432-2234
    Keywords: Polarized basis sets ; Atomic dipole polarizabilities of Pb, Bi, Po, and At ; Molecular electric properties ; Dipole moments and polarizabilities of the fifth-row hydrides ; Relativistic contributions to atomic and molecular properties ; PbH4 ; BiH3 ; PoH2 ; AtH
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The first-order polarized basis sets for the use in high-level-correlated investigations of molecular electric properties have been generated for Pb, Bi, Po, and At. The performance of the standard [10.17.14.5/13.11.8.2] and extended [20.17.14.9/13.11.8.4] basis sets has been examined in nonrelativistic and quasirelativistic calculations for atoms and simple closed-shell hydrides. The relativistic contributions to electric dipole properties of those systems have been evaluated by using the recently developed quasirelativistic scheme. The predicted dipole polarizability of At is in good agreement with the results of other relativistic calculations. The calculated quasirelativistic dipole moments of BiH3 (−0.499 a.u.), PoH2 (−0.207 a.u.), and AtH (+0.036 a.u.) involve a significant relativistic contribution which amounts to —0.230 a.u., −0.177 a.u., and −0.097 a.u., respectively. The basis set details append this paper. They are also available as a part of the basis set library of the MOLCAS system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01113061
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