Relativistic four-component MRCISD+Q calculations of the six lowest valence states of molecular I 2 − anion...

This study aimed to obtain potential energy curves within a multireference 4-component relativistic method and to present spectroscopic constants (R${}_e$,${\omega }_e$,${\omega }_e$x${}_e$,${\omega }_e$y${}_e$, D${}_e$, D${}_0$, B${}_e$,${\alpha }_e$,${\beta }_e$,${\gamma }_e$), accurate extended Rydberg analytical form, and rovibrational levels for the 6 low-lying states of the I${}_2^{-}$ anion. For these states, some spectroscopic constants, rovibrational levels, and an accurate analytical form are presented for the first time in literature, and they are of interest for femtosecond and dynamics experiments of I${}_2^{-}$ as well as for electron attachment of I${}_2$. This study suggests that the inclusion of relativistic and correlation effects treated at the MRCISD+Q level is needed to obtain reliable results, specially for D${}_e$.

The potential energy curves of the ground and the excited states of the molecular iodine anion (I${}_2^{-}$) were investigated at multireference configuration interaction (MRCISD) with Davidson size-extensivity correction (denoted as +Q) within a fully relativistic four-component relativistic framework including Breit interaction.