Abstract
Ionization potentials (IP’s) are evaluated for various excited states of Tl using the relativistic coupled cluster (CCCD) theory in the even-parity pair channel approximation (CCSD-EPC). An average accuracy below half a percent is reached. The effect of deep core electrons on the core-valence correlations is investigated. It is found that electrons in the third subshell modify the IP’s of the orbitals by By comparison with calculations made in the linearized CCSD (LCCSD) approximation it is demonstrated that nonlinear contributions are mandatory to reach an accuracy below half a percent for the orbital.
- Received 4 August 2000
DOI:https://doi.org/10.1103/PhysRevA.63.022507
©2001 American Physical Society