Excited states of PbF: a four-component relativistic study.
The electronic states of lead monofluoride (PbF) are studied from the (Pb 6s)(2) (F 2p-pi)(4) (F 2p-sigma)(2) (Pb 6p-pi)(1) X(1) ground state up to the F state, using the four-component relativistic configuration interaction and Fock-space coupled-cluster singles and doubles methods. Difficulties arising from the valence-Rydberg mixing are overcome by using a flexible basis set including Rydberg-type diffuse functions and by large-scale correlation calculations. The excited states are successfully characterized with the help of computed transition dipole moments. The three lowest-lying states (X(1), X(2), and A) are confirmed to be valence states arising from the (Pb 6p) spinors. The B state is assigned to the lowest Rydberg state (Omega=1/2), represented by a single excitation from the (Pb 6p-pi) spinor to the (F 3s) Rydberg spinor. Its calculated excitation energy (4.30 eV) is comparable to the observed one (4.42 eV). The C state is a multiconfigurational valence state whose dominant configuration is represented by (Pb 6s)(2) (F 2p-pi)(4) (F 2p-sigma)(1) (Pb 6p-pi)(2). Its calculated excitation energy (4.71 eV) is in good agreement with experiment (4.72 eV). The remaining D, E, and F states are assigned as Rydberg states. The calculated ionization potential (7.44 eV) is also close to the value (7.55 eV) determined recently by multiphoton ionization experiments.
School of International Liberal Studies, Chukyo University, 101-2 Yagoto-Honmachi, Showa-ku, Nagoya, Aichi 466-8666, Japan. syamamot@lets.chukyo-u.ac.jp
Shigeyoshi
S
Yamamoto
Hiroshi
H
Tatewaki