Double ionization energies of HCl, HBr, Cl2 and Br2 molecules: An MRCI study

Accurate double ionization energies (DIEs) for low-lying doubly charged states of HCl, HBr, Cl2 and Br2 were calculated using non-relativistic CASSCF/MRCI level of theory with the aug-cc-pVQZ basis set. The results are in excellent agreement with experimental data, presenting absolute average deviations lower than 0.3 eV. Some DIEs not previously assigned or well characterized are discussed. Further improvements can be reached by including relativistic effects.