Relativistic treatment for energy levels and oscillator strength of the lithium atom

doi:10.7523/j.issn.2095-6134.2012.4.002

Abstract

Abstract:

Relativistic multichannel theory is used to calculate eigen quantum defects of 1s²ns ²S, 1s²np ²P, 1s²nd ²D, and 1s²nf ²F of lithium, and then the quantum defect functions are fitted. Ionization potentials and quantum defects of 1s²np ²P(n=7~60) are obtained, and the results are in good agreement with the latest experiment. Using the relativistic configuration interaction method, the dipole transition oscillator strength of 1s²2s→1s²np_1/2 are also calculated, and the calculations show that inclusion of one- and two-electron excitation configurations will significantly improve the results.

Key words: relativistic multichannel theory, configuration interaction theory, quantum defect, oscillator strength

CLC Number:

O562

WANG Ze, QU Yi-Zhi, HU Xiao-Li. Relativistic treatment for energy levels and oscillator strength of the lithium atom[J]. , 2012, 29(4): 439-448.

References

[1] Wang Z W,Zhu X W, Chung K T.Energy and fine structure of 1s²nd and 1s²nf states for the lithium isoelectronic sequence[J].J Phys B,1992,25:3915-3927.
[2] Rothery N E,Storry C H, Hessels E A.Precision radio-frequency measurements of the high-L Rydberg states of lithium[J].Phys Rev A,1995,51(4):2919-2925.
[3] Richard J D, Bhatia A K.Rydberg levels of lithium[J].Phys Rev A,1995,51(4):2926-2930.
[4] Storry C H,Rothery N E, Hessels E A.Measurement of the n=9 F-to-G intervals in atomic lithium[J].Phys Rev A,1997,55(1):128-133.
[5] Bhatia A K, Richard J D.Relativistic,retardation,and radiative corrections in Rydberg states of lithium[J].Phys Rev A,1997,55(3):1842-1845.
[6] Chen C, Wang Z W.Energies of 1s²ng and 1s²nh(n=5,6,7, and 8)states for lithium isoelectronic sequence[J].Commun Theor Phys,2005,43(5):886-890.
[7] Chen C, Wang Z W.Resonance calculations of d-f intervals for the lithium Rydberg states[J].Chin Phys Soc,2005,14(3):505-510.
[8] Goy P,Liang J,Gross M,et al.Quantum defects and specific-isotopic-shift measurement in ns and np highly excited states of lithium:Exchange effects between Rydberg and core electrons[J].Phys Rev A,1986,34(4):2889-2896.
[9] Haq M A,Mahmood S,Riaz M,et al.On the first ionization potential of lithium[J].J Phys B,2005,38:S77-S86.
[10] Bushaw B A,Nortershauser W,Drake G W,et al.Ionization energy of ^6,7Li determined by triple-resonance laser spectroscopy[J].Phys Rev A,2007,75(052503):1-8.
[11] Oxley P,Collins P.Frequency stabilization of multiple lasers and Rydberg atom spectroscopy[J].Appl Phys B,2010,101:23-31.
[12] Chen C.Ionization potentials and puantum defects of 1s²np ²P Rydberg states of lithium atom[J].Commun Theor Phys,2008,50(3):733-737.
[13] Zhao Z X,Li J M. Non-relativistic and relativistic atomic configuration interaction theory[J].Chin Phys,1985,34(11):1469-1478(in Chinese). 赵中新,李家明.非相对论性和相对论性原子组态相互作用理论[J].物理学报,1985,34(11):1469-1478.
[14] Fano U, Lee C M.Variational calculation of R matrices. application to Ar photoabsorption[J].Phys Rev Lett,1973,31(27):1573-1576.
[15] Lee C M, Lu K T.Spectroscopy and collision theory. II. The Ar absorption spectrum[J].Phys Rev A,1973,8(3):1241-1257.
[16] Lee C M.Spectroscopy and collision theory. III. Atomic eigenchannel calculation by a Hartree-Fock-Roothaan method[J].Phys Rev A,1974,10(2):584-600.
[17] Huang W,Zou Y,Tong X M,et al.Atomic energy levels and Lande g factors: A theoretical study[J].Phys Rev A,1995,52(4):2770-2777.
[18] Zou Y,Tong X M,Li J M.Relativistic multichannel theory of atomic structure[J].Chin Phys,1995,44(1):50-56(in Chinese). 邹宇,仝晓民,李家明.原子结构的相对论性多通道理论[J].物理学报,1995,44(1):50-56.
[19] Qu Y Z,Peng Y L.Relativistic multichannel treatment of krypton spectra across the first ionization threshold[J].Chin Phys Lett,2005,22(8):1884-1886.
[20] Fan S L,Li X M,Jia F D,et al.Relativistic multichannel treatment of the autoionization Rydberg series 3ds(¹D₂)np²P_1/2 of scandium[J].J Phys B,2010,43(13502):1-8.
[21] Li J M,Zhao Z X.Variation in L,M,N inner-shell electron binding energies of rare-earth elements in valence transition[J].Chin Phys,1982,31(1):97-103(in Chinese). 李家明,赵中新.变价稀土元素L,M,N内壳层电子束缚能的变化[J].物理学报,1982,31(1):97-103.
[22] Slater J C.Notes on Hartree's method[J].Phys Rev,1930,35:210-211.
[23] Kohn W, Sham L J.Self-consistent quations including exchange and correlation effects[J].Phys Rev,1965,140(4A):1133-1138.
[24] Chen C,Han X Y, Li J M.Calculations of high Rydberg states for the lithium atom[J].Phys Rev A,2005,71(042503):1-6.
[25] Wang H C,Qu Y Z,Liu C H.Relativistic configuration interaction treatment of generalized oscillator strength for Krypton[J].Chin Phys Lett,2007,24(7):1901-1903.
[26] Zou Y,Fang Q Y,Li J M.Relativistic multichannel theory: doubly excited states of atomic helium[J].Chin Phys Lett,1998,15(3):175-177.
[27] Ralchenko Y,Kramida A E,Reader J,et al.NIST atomic spectra database(version 3.1.5) .(2008) .http://physics.nist.gov/asd3.
[28] Wiese W L, Fuhr J R.Accurate atomic transition probabilities for hydrogen, helium, and lithium[J].J Phys Chem Ref Data,2009,38(3):565-719.
[29] Martin W C, Wiese W L.Atomic spectroscopy //Springer Handbook of Atomic, Molecular, and Optical Physics,Part B,Ch 10:175-198, 2006 .New York: Springer Science Inc. http://www.springerlink.com/content/g312207pr62t3072/.
[30] Sansonetti J E, Martin W C. Handbook of basic atomic spectroscopic data[J].J Phys Chem Ref Data,2005,34(4):1559-2259.
[31] Wiese W L,Smith M W, Glennon B M.Atomic transition probabilities, Vol. I: Hydrogen through neon-A critical data compilation .Nat Stand Ref Data Ser, NSRDS-NBS 4: 153.(U.S. Government Printing Office, Washington DC, 1966) . http://www.nist.gov/data/nsrds/NSRDS-NBS4.pdf.