Theoretical Investigation on excited dipole bound states of alkali-containing diatomic anions

Abstract

Abstract Information about electronic excited states of molecular anions plays an important role in investigating the electron attachment and detachment processes. Here we present a high-level theoretical study on the electronic structures of twelve alkali-metal-containing diatomic anions MX- (MX = LiH, LiF, LiCl, NaF, NaCl, NaBr, RbCl, KCl, KBr, RbI, KI, and CsI). The equation-of-motion electron-attachment coupled-cluster singles and doubles (EOM-EA-CCSD) method is carried out to calculate the electron binding energies (EBEs) of 10 electronic excited states of each of the twelve molecule anions. With addition of different s-/p-/d- diffusion functions in the basis set, we have identified possible excited dipole bound states (DBSs) of each anion. With the investigation of EBEs on the twelve MXs with dipole moment (DM) up to 12.1 D, we evaluate the dependence of the number of anionic excited DBSs on molecular DM. The results indicate that, there exists at least two or three DBSs of anions with the molecular DM larger than 7 D and a molecule with DM > 10 D can sustain a π-DBS of the anion. Our study would shed some implications on the excited DBSs electronic states of alkali-metal-containing diatomic molecules.