Ab initio study on transition properties of LaO molecular

doi:10.3969/j.issn.1000-1565.2020.02.003

Abstract

Abstract: By employing a quantum chemical calculation method,we computed the electronic structure and radiative properties of LaO molecule.The potential energy curves and permanent dipole moment(PDM)of three low-lying Λ-S electronic states and transition diploe moment(TDM)of the A²Π_r → X²Σ⁺ and the A²Π_r → A^'2Δ_r transition of the LaO molecule have been calculated at the multi-reference configuration interaction(MRCI)level of theory.The spectroscopic constants derive from our present work are in good agreement with previous theoretical and experimental values.We also achieved the Franck-Condon Factors(FCFs)and spontaneous radiative lifetimes for the A²Π_r → X²Σ⁺ transition based on the obtained potential energy curve and TDM.Moreover,we chose the same space orbits and basis set in subsequent calculations for the spin-orbit coupling at MRCI level.The PECs and the spectroscopic parameters together with previous theoretical value for the five Ω states are shown in the paper.These results will be beneficial for the related experimental.

Key words: excited states, potential energy curves, spin-orbit coupling, Franck-Condon factors

CLC Number:

O152

TIAN Ying,JIANG Gang. Ab initio study on transition properties of LaO molecular[J]. Journal of Hebei University (Natural Science Edition), 2020, 40(2): 125-131.

References

[1] CHU S,HOLLBERG L,BJORKHOLM J E,et al.Three-dimensional viscous confinement and cooling of atoms by resonance radiation pressure[J].Physical Review Letters,1985,55(1): 48.DOI:10.1103/physrevlett.55.48.
[2] LETT P D,WATTS R N,WESTBROOK C I,et al.Observation of atoms laser cooled below the Doppler limit[J].Physical Review Letters,1988,61(2): 169.DOI:10.1103/physrevlett.61.169.
[3] ANDERSON M H,ENSHER J R,MATTHEWS M R,et al.Observation of Bose-Einstein condensation in a dilute atomic vapor[J].Science,1995,269(5221): 198-201.DOI:10.1126/science.269.5221.198.
[4] DAVIS K B,MEWES M O,ANDREWS M R,et al.Bose-Einstein condensation in a gas of sodium atoms[J].Physical Review Letters,1995,75(22): 3969.DOI:10.1103/physrevlett.75.3969.
[5] BRADLEY C C,SACKETT C A,TOLLETT J J,et al.Evidence of Bose-Einstein condensation in an atomic gas with attractive interactions[J].Physical Review Letters,1995,75(9): 1687.DOI:10.1103/physrevlett.75.1687.
[6] SHUMAN E S,BARRY J F,DEMILLE D.Laser cooling of a diatomic molecule[J].Nature,2010,467(7317): 820-823.DOI:10.1038/nature09443.
[7] HUMMON M T,YEO M,STUHL B K,et al.2D magneto-optical trapping of diatomic molecules[J].Physical Review Letters,2013,110(14): 143001.DOI:10.1103/physrevlett.110.143001.
[8] WALL T E,KANEM J F,HUDSON J J,et al.Lifetime of the A(v'=0)state and Franck-Condon factor of the A-X(0-0)transition of CaF measured by the saturation of laser-induced fluorescence[J].Physical Review A,2008,78(6): 062509.DOI:10.1103/physreva.78.062509.
[9] WAN M J,SHAO J X,GAO Y F,et al.Laser cooling of MgCl and MgBr in theoretical approach[J].The Journal of Chemical Physics,2015,143(2): 024302.DOI:10.1063/1.4926389.
[10] GAO Y F,GAO T.Laser cooling of the alkaline-earth-metal monohydrides: Insights from anab initiotheory study[J].Physical Review A,2014,90(5): 052506.DOI:10.1103/physreva.90.052506.
[11] ISAEV T A,HOEKSTRA S,BERGER R.Laser-cooled RaF as a promising candidate to measure molecular parity violation[J].Physical Review A,2010,82(5): 052521.DOI:10.1103/physreva.82.052521.
[12] YANG Q S,GAO Y F,YU Y,et al.Ab initio study of the feasibility of laser cooling of ScO molecule[J].Molecular Physics,2016,114(6): 870-875.DOI:10.1080/00268976.2015.1129461.
[13] HERZBERG G.Molecular spectra and molecular structure I,spectra of diatomic molecules[M].New York: Van Nostrand Reinhold,1957.
[14] T RRING T,ZIMMERMANN K,HOEFT J.The microwave rotational spectrum of X 2Σ LaO[J].Chemical Physics Letters,1988,151(6): 520-525.DOI:10.1016/s0009-2614(88)85030-9.
[15] HONG G Y,DOLG M,LI L M.A comparison of scalar-relativistic ZORA and DKH density functional schemes: monohydrides,monooxides and monofluorides of La,Lu,Ac and Lr[J].Chemical Physics Letters,2001,334(4/5/6): 396-402.DOI:10.1016/S0009-2614(00)01430-5.
[16] SCHOONVELD L,SUNDARAM S.Electronic transitions of LaO molecule[J].The Astrophysical Journal Supplement Series,1974,27: 307.DOI:10.1086/190298.
[17] KOREK M,EL-KORK N,MOUSSA A N,et al.Theoretical study with rovibrational and dipole moment calculation of the LaO molecule[J].Chemical Physics Letters,2013,575: 115-121.DOI:10.1016/j.cplett.2013.05.006.
[18] HUBER K P,HERZBERG G.Molecular spectra and molecular structure IV constants of diatomic molecules[M].New York: Van Nostrnad-Reinhold,1979.
[19] CARETTE P.The ultraviolet emission spectrum of LaO[J].Journal of Molecular Spectroscopy,1990,140(2): 269-279.DOI:10.1016/0022-2852(90)90140-l.
[20] BERNARD A,VERGÉ S J.The infrared A2Π→A' 2Δ transition of LaO[J].Journal of Molecular Spectroscopy,2000,201(1): 172-174.DOI:10.1006/jmsp.2000.8077.
[21] WERNER H J,KNOWLES P J.A second order multiconfiguration SCF procedure with optimum convergence[J].The Journal of Chemical Physics,1985,82(11): 5053-5063.DOI:10.1063/1.448627.
[22] KNOWLES P J,WERNER H J.An efficient second-order MC SCF method for long configuration expansions[J].Chemical Physics Letters,1985,115(3): 259-267.DOI:10.1016/0009-2614(85)80025-7.
[23] WERNER H J,KNOWLES P J.An efficient internally contracted multiconfiguration–reference configuration interaction method[J].The Journal of Chemical Physics,1988,89(9): 5803-5814.DOI:10.1063/1.455556.
[24] KNOWLES P J,WERNER H J.An efficient method for the evaluation of coupling coefficients in configuration interaction calculations[J].Chemical Physics Letters,1988,145(6): 514-522.DOI:10.1016/0009-2614(88)87412-8.
[25] LANGHOFF S R,DAVIDSON E R.Configuration interaction calculations on the nitrogen molecule[J].International Journal of Quantum Chemistry,1974,8(1): 61-72.DOI:10.1002/qua.560080106.
[26] FAHS H,ALLOUCHE A R,KOREK M,et al.Theoretical electronic structure of the lowest-lying states of the LaF molecule[J].The Journal of Chemical Physics,2002,117(8): 3715-3720.DOI:10.1063/1.1493769.
[27] WERNER H J, KNOWLES P J, et al. MOLPRO.a Package of Ab initio programs[DB/OL]. [2019-01-20]. http://www.molpro.net/.
[28] KENDALL R A,DUNNING T H Jr,HARRISON R J.Electron affinities of the first-row atoms revisited:Systematic basis sets and wave functions[J].The Journal of Chemical Physics,1992,96(9): 6796-6806.DOI:10.1063/1.462569.
[29] LE ROY R J. Level 8.0: A computer program for solving the radial schrödinger equation for bound and quasibound levels[DB/OL]. [2019-01-20]. http://scienide2.uwaterloo.ca/.
[30] STEIMLE T C,VIRGO W.The permanent electric dipole moments for the A²Π and B^'2Σ⁺ states and the hyperfine interactions in the A^'2Π state of lanthanum monoxide,LaO[J].The Journal of Chemical Physics,2002,116(14): 6012-6020.DOI:10.1063/1.1458245.