**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.**