ABSTRACT:The lowest-lying states of the species GeC, GeC ϩ , GeSi, and GeSi ϩ were studied using the multireference configuration interaction (MRCI) method and the aug-cc-pVQZ basis set. For the first time, the GeC ϩ molecule was characterized. The dissociation energy (D 0 ) of the ground state (X 3 ͟) of GeC is equal to 3.70 eV, showing good agreement with the theoretical result (3.90 eV) of Sari and colleagues. These results, however, are considerably smaller than the experimental value of 4.72 eV. The dissociation energy of the ground state (X 3 ¥ Ϫ