title: Potential Energy Curves in the CASSCF/CASPT2 and FS-MR-CC Methods: The Role of Relativistic Effects.
abstract: Ab initio CASSCF/CASPT2 calculations for the electronic ground and for a wide range of excited states of Li2 and Na2 dimers are presented. The computed spectroscopic parameters agree very well with the experimental data. This indicates that the old CASSCF/CASPT2 method can be as successfully applied to study excited states of molecules as recently developed the multireference Fock-space coulped-cluster method. The role of relativistic effects in the correct description of the potential energy curves has been investigated using as an example the SiAu molecule. The accuracy of the new infinite-order two-component relativistic method has been studied and its advantage over the Douglas-Kroll-Hess method demonstrated.
authors.affiliation: Department of Quantum Chemistry, Faculty of Chemistry, Nicolaus Copernicus University , Gagarina 7, 87-100 Toruń, Poland.
authors.forename: Maria
authors.initials: M
authors.lastname: Barysz