A b i n i t i o calculations on the four lowest electronic states of AlF+ and AlCl+

Abstract

The potential energy curves of the two lowest 2Σ+ (X,B) and the two lowest 2Π (A,C) electronic states of the AlF+ and AlCl+ molecular ions have been calculated using highly correlated multireference configuration interaction (MR-CI) wave functions. It is found that both 2Σ+ states and the C 2Πr state are bound, whereas the A 2Πi state is repulsive. Electronic transition moment functions for all six pairs of states of both ions have also been calculated and used for evaluation of the radiative transition probabilities between bound vibrational states. The calculated charge distributions show that the X and C states are dominated by Coulombic attraction between a doubly charged positive aluminum and the singly charged negative halogen ion. The results provide a new assignment of the photoelectron spectra of the neutral AlF. They are also in good agreement with the recently observed optical B–X emission spectra of both molecular ions and C–X bands of AlCl+. The absence of C–X emission of AlF+ is most likely due to predissociation of the C 2Πr state by the repulsive A 2Πi state.

Theoretical investigation of the GaF molecule and its positive ion

“…The closeness in the results for AlCl with those in Ref. [29] may be coincidental. Thus Al makes a bond with Cl that is 1.7 times stronger than Ga bonds to Cl.…”

“…Thus the Ga atom appears to be doubly charged even in GaF , as has been noted by Yoshikawa and Hirst [28]. Such high ionicity induced by F has also been noted by Glenewinkel-Meyer et al [29] for AlF , based on their extensive all-electron CASSCF/MRCI calculations. Two sets of MRCPA-4 (and MRCI) calculations on GaF were carried out using the following four reference con®gurations:…”

“…The experimental h e of AlF is 3X14 AE 0X14 eV [30], verifying the reliability of Ref. [29]. Simple SCF/CI calculations done by Mochizuki et al [31] yielded estimates of 1.09 eV for h e (GaCl ) and 1.82 eV for h e (AlCl ).…”

“…Glenewinkel-Meyer et al carried out high-level CASSCF/MRCI calculations with extended basis sets on AlF and AlCl and obtained h e values of 2.98 eV for the former and 1.72 eV for the latter [29], that is, the F bond to Al is 1.7 times stronger than that of Cl to Al . The experimental h e of AlF is 3X14 AE 0X14 eV [30], verifying the reliability of Ref.…”

Extensive theoretical studies on the low‐lying electronic states of indium monochloride cation, InCl+

“…The low‐lying electronic states of some IIIA group cationic monohalides, such as BBr + ,11 AlF + ,12 AlCl + ,12 GaF + ,13 and GaCl + ,13 have been extensively investigated theoretically. In contrast, so far the only theoretical study on InCl + was due to Schwerdtfeger et al14 They reported the spectroscopic constants of the ground state at various levels of theory.…”