Energetic degeneracy and electronic structures of germanium trimers doped with titanium

Abstract

Geometries and electronic structures of germanium trimer clusters doped with titanium TiGe-/0 3 were studied making use of the CASSCF/CASPT2, CCSD(T)-F12, and TPSS methods. Three used quantum chemical methods pointed out that the most stable geometries of both neutral and cationic clusters TiGe-/0 3 have a pyramid shape (C 3v and C s spatial symmetries). Two electronic states (2 A' and 2 A") of the anion were determined to be nearly degenerate and energetically competing for the anionic ground state of TiGe-3. These two states are believed to be concurrently populated in the experiment, and contribute to all visible anion photoelectron bands in the experimental spectrum. Total 14 electronic transitions starting from the 2 A' and 2 A" states were predicted to be underlying 5 out of 6 visible bands in the experimental anion photoelectron spectrum of TiGe-3. Each band was proven to be caused by multiple one-electron detachments from two populated anionic states. The last experimental band with the highest detachment energy is believed to be the result of various inner one-electron removals. Multidimensional Franck-Condon factor simulations of two first transitions where vibrational frequencies of three involved states are accessible were conducted to give more details to the lowest-ionization band.