Ab initio study of low-lying triplet states of the lithium dimer
2005 (English)In: Spectrochimica Acta Part A - Molecular and Biomolecular Spectroscopy, ISSN 1386-1425, Vol. 62, no 4-5, 790-799 p.Article in journal (Refereed) Published
Observation of Bose-Einstein condensation in Li-7(2) initiated the interest in the scattering length of two ground state lithium atoms when they approach each other as a radical pair triplet a(3)Sigma(u)(+) state. But some properties of this state are still unknown. In present work, a number of low-lying triplet states of lithium molecule are calculated by multi-configuration self-consistent field (MCSCF) and response techniques with account of spin-orbit coupling, spin-spin coupling and some other magnetic perturbations. The singlet-triplet transition probabilities to the ground state are also presented. Most results are connected with the weakly bound lowest triplet a(3)Sigma(u)(+) state, whose radiative lifetime and spin-splitting are unknown so far in spite of its great importance in Bose-Einstein condensation. Calculations indicate that this state has a very small spin-splitting, lambda(ss) = -0.01 cm(-1), which is negligible in comparison with the line-width in experimental Fourier transform C spectra published so far. Similar splitting is obtained for the upper state of the 1(3)Sigma(g)(+)-a(3)Sigma(u)(+) transition. This is in agreement with experimental rovibronic analysis of the 1(3)Sigma(g)(+)- a(3)Sigma(u)(+) band system in which the triplet structure was not resolved. The radiative lifetime of the a(3)Sigma(u)(+) state is predicted to exceed 10 h.
Place, publisher, year, edition, pages
2005. Vol. 62, no 4-5, 790-799 p.
lithium dimer, triplet states, zero-field splitting, spin-spin coupling
IdentifiersURN: urn:nbn:se:kth:diva-37847DOI: 10.1016/j.saa.2005.03.006ISI: 000233930600005ScopusID: 2-s2.0-27844592128OAI: oai:DiVA.org:kth-37847DiVA: diva2:435597
QC 201108192011-08-192011-08-182011-08-19Bibliographically approved