The dissociation curves for the ground states of Tl2 and Tl2+ were computed using a generalization of the molecular relativistic ω–ω coupling formalism of Lee, Ermler, and Pitzer. Relativistic effects, as represented by the Dirac equation, were introduced using effective potentials generated from atomic Dirac–nFock wave functions using a generalization of the improved effective potential formulation of Christiansen, Lee, and Pitzer. Our calculations show that the ground state of Tl2+ is 1/2g with computed De and Re values of 0.58 eV and 3.84 A. For Tl2 we find that the ground state is 0u− but the 0g+ and the 1u states are only slightly higher in energy; the potential curves for these states are repulsive to about 3.5 A and then essentially flat beyond that radius. While corrections for correlation will increase De somewhat, Tl2 is only weakly bound in any of these states which dissociate to normal atoms. The cause is undoubtedly related to the large spin‐orbit splitting between the 6p1/2 and 6p3/2 thallium spinors.The dissociation curves for the ground states of Tl2 and Tl2+ were computed using a generalization of the molecular relativistic ω–ω coupling formalism of Lee, Ermler, and Pitzer. Relativistic effects, as represented by the Dirac equation, were introduced using effective potentials generated from atomic Dirac–nFock wave functions using a generalization of the improved effective potential formulation of Christiansen, Lee, and Pitzer. Our calculations show that the ground state of Tl2+ is 1/2g with computed De and Re values of 0.58 eV and 3.84 A. For Tl2 we find that the ground state is 0u− but the 0g+ and the 1u states are only slightly higher in energy; the potential curves for these states are repulsive to about 3.5 A and then essentially flat beyond that radius. While corrections for correlation will increase De somewhat, Tl2 is only weakly bound in any of these states which dissociate to normal atoms. The cause is undoubtedly related to the large spin‐orbit splitting between the 6p1/2 and 6p3/2 thalliu...
[1]
G. Herzberg.
Molecular Spectra and Molecular Structure IV. Constants of Diatomic Molecules
,
1939
.
[2]
D. S. Ginter,et al.
Electronic Spectra of the Ga2, In2, and Tl2 Molecules
,
1965
.
[3]
R. Miller,et al.
Velocity Distributions in Potassium and Thallium Atomic Beams
,
1955
.
[4]
P. A. Christiansen.
ELECTRONIC STRUCTURE FOR THE GROUND STATE OF T1H FROM RELATIVISTIC MULTICONFIGURATION SCF CALCULATIONS
,
1980
.
[5]
P. A. Christiansen,et al.
IMPROVED Ab Initio EFFECTIVE CORE POTENTIALS FOR MOLECULAR CALCULATIONS
,
1979
.
[6]
W. R. Wadt.
The electronic states of Ar + 2 , Kr + 2 , Xe + 2 . I. Potential curves with and without spin-orbit coupling
,
1978
.
[7]
W. C. Ermler,et al.
Abinitio effective core potentials including relativistic effects. V. SCF calculations with ω–ω coupling including results for Au2+, TlH, PbS, and PbSe
,
1980
.
[8]
E. Commins,et al.
Preliminary Observation of Parity Nonconservation in Atomic Thallium
,
1979
.
[9]
J. Berkowitz,et al.
Photoionization of High‐Temperature Vapors. IV. TlF, TlCl, and TlBr
,
1968
.
[10]
J. Drowart,et al.
A mass spectrometric method for the determination of dissociation energies of diatomic molecules
,
1957
.
[11]
Kenneth S. Pitzer,et al.
RELATIVISTIC EFFECTS ON CHEMICAL PROPERTIES
,
1979
.