Thermochemical spin‐orbit corrections for platinum cation (Pt+)

• Published in: International journal of quantum chemistry 2021-02, Vol.121 (4), p.n/a
• Main Author: Irikura, Karl K.
• Format: Article
• Language: English
• Subjects: atomization energy; Chemistry; Energy levels; excited states; Mathematical analysis; Physical chemistry; Platinum; promotion energy; Quantum physics; spin‐orbit correction; spin‐orbit coupling; Thermochemistry
• ISSN: 0020-7608; 1097-461X
• DOI: 10.1002/qua.26448

In quantum thermochemistry, many atoms require spin‐orbit corrections to compensate for the lack of spin‐orbit coupling in most calculations. When terms or configurations are strongly mixed, as they are in Pt+, naïve averaging of experimental data produces erroneous corrections. Here, spin‐orbit calculations provide the composition of observed energy levels in LS (Russell‐Saunders) terms. The compositional data are combined with the experimental energy levels to obtain averaged term energies for Pt+, including the ground‐term spin‐orbit correction. For ground‐state Pt+, a correction of (−4251 ± 136) cm−1 or (−50.8 ± 1.6) kJ mol−1 is recommended. The recommended value for the 2D‐4F excitation energy, which represents the nominal 5d‐6s promotion energy, is (7112 ± 225) cm−1. For anionic Pt−, simple J‐averaging is appropriate, and the ground‐state spin‐orbit correction is (−3896.4 ± 0.2) cm−1 or (−46.611 ± 0.002) kJ mol−1. Most calculations ignore spin‐orbit coupling and require empirical spin‐orbit corrections. When LS terms mix strongly, as they do in Pt+, the spin‐orbit corrections cannot be derived from experimental data alone.