Effective bond orders from two-step spin-orbit coupling approaches: the I2, At2, IO(+), and AtO(+) case studies.
The nature of chemical bonds in heavy main-group diatomics is discussed from the viewpoint of effective bond orders, which are computed from spin-orbit wave functions resulting from spin-orbit configuration interaction calculations. The reliability of the relativistic correlated wave functions obtained in such two-step spin-orbit coupling frameworks is assessed by benchmark studies of the spectroscopic constants with respect to either experimental data, or state-of-the-art fully relativistic correlated calculations. The I2, At2, IO(+), and AtO(+) species are considered, and differences and similarities between the astatine and iodine elements are highlighted. In particular, we demonstrate that spin-orbit coupling weakens the covalent character of the bond in At2 even more than electron correlation, making the consideration of spin-orbit coupling compulsory for discussing chemical bonding in heavy (6p) main group element systems.
SUBATECH, CNRS UMR 6457, IN2P3/EMN Nantes/Université de Nantes, 4 rue Alfred Kastler, BP 20722, 44307 Nantes Cedex 3, France.
Rémi
R
Maurice
Laboratoire PhLAM, CNRS UMR 8523, Université de Lille, 59655 Villeneuve d'Ascq Cedex, France.
Florent
F
Réal
Laboratoire PhLAM, CNRS UMR 8523, Université de Lille, 59655 Villeneuve d'Ascq Cedex, France.
André Severo Pereira
AS
Gomes
Laboratoire PhLAM, CNRS UMR 8523, Université de Lille, 59655 Villeneuve d'Ascq Cedex, France.
Valérie
V
Vallet
SUBATECH, CNRS UMR 6457, IN2P3/EMN Nantes/Université de Nantes, 4 rue Alfred Kastler, BP 20722, 44307 Nantes Cedex 3, France.
Gilles
G
Montavon
CEISAM, UMR CNRS 6230, Université de Nantes, 2 rue de la Houssinière, BP 92208, 44322 Nantes Cedex 3, France.
Nicolas
N
Galland