AbstractAbstract
[en] In order to optimize basis sets for future molecular calculations, the energies and dipole polarizabilities of 1S, 3P, and 1P states of Zn, Cd, and Hg have been determined from Hartree--Fock (HF) and multiconfiguration calculations. These utilize either empirically fitted pseudopotentials or ab initio effective core potentials (ECP). Our calculated polarizabilities for ground state atoms agree within 10% with recommended values so long as either the empirical pseudopotentials or the ECP based on relativistic HF calculations are used. Our calculations agree with the measured anisotropy of the polarizability of 3P1 Hg, but disagree with measured values of the 3P2 state anisotropy. Our calculated 3P2 anisotropy is consistent with both the measured and calculated 3P1 Hg anisotropy; the measured 3P2 values are not. We find calculations based on nonrelativistic ECP to give incorrect polarizabilities
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Journal of Chemical Physics; ISSN 0021-9606; ; v. 72(4); p. 2525-2531
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AbstractAbstract
[en] Collision induced absorption at either the pump or Stokes wavelength could reduce the efficiency of Raman scattering of XeCl pump radiation in Pb vapor. Calculation of the collision induced absorption requires a knowledge of the different energy curves between the ground and upper states and the transition moment as a function of the internuclear distance. These curves were obtained in a first-order configuration interaction calculation of the PbHe, PbHe+, PbXe, and PbXe+ valence states. The atomic cores of Pb and Xe were replaced by relativistic effective core potentials so as to make the calculations tractable. The van der Waals interaction was also estimated by a variational perturbation calculation. These results were transformed to an Ω representation using an empirically determined spin--orbit operator. Using these theoretical data we estimate the collision induced absorption cross sections to be 10-23 and 10-21 cm2 per atmosphere of Xe for the first and second Stokes lines in the case of a 308.0 nm pump. Cross sections for He will be about an order of magnitude smaller due to the smaller transition moments. The energy defect for the pump wavelength is estimated to be so large that no significant absorption is expected for either PbXe or PbHe collision partners. There are also no calculated curve crossings at an energy lower than 0.25 eV, which indicates a very small probability for deactivation of Pb(3P2) by rare gas collision
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Journal of Chemical Physics; ISSN 0021-9606; ; v. 73(12); p. 6247-6258
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