GRECP/5e-MRD-CI calculation of the electronic structure of PbH
Authors: T.A. Isaev, N.S. Mosyagin, A.V. Titov, A.B. Alekseyev, R.J.
Buenker
Comments: 6 pages, submitted to Int.J.Quatn.Chem
The correlation calculation of the electronic
structure of PbH is carried out with the
Generalized Relativistic Effective Core
Potential (GRECP) and MultiReference single-
and Double-excitation Configuration Interaction
(MRD-CI) methods. The 22-electron
GRECP for Pb is used and the outer core
5s, 5p and 5d pseudospinors are frozen
using the level-shift technique, so only
five external electrons of PbH are correlated. A
new configuration selection scheme with
respect to the relativistic multireference states
is employed in the framework of the MRD-CI
method. The [6,4,3,2] correlation
spin-orbit basis set is optimized in the
coupled cluster calculations on the Pb atom
using a recently proposed procedure, in
which functions in the spin-orbital basis set are
generated from calculations of different
ionic states of the Pb atom and those functions
are considered optimal which provide the
stationary point for some energy functional.
Spectroscopic constants for the two lowest-lying
electronic states of PbH
($^2\Pi_{1/2}, ^2\Pi_{3/2}$) are found
to be in good agreement with the
experimental data.