Electronic structure of the mixed aluminum and sodium cluster Al2Na

Electronic structure of Al2Na was reinvestigated using MP2, CCSD(T) and MRMP2/CASSCF(7,7) calculations with aug-cc-pVnZ (n = D, T and Q) basis sets. In contrast to a recent report, the triangular Al2Na has a 2B1 ground state with a 4B1–2B1 gap of 2.5 kcal/mol, rather than a 2A1 state (13.7 kcal/mol higher). In addition, Al2Na+ exhibits a linear 1Σ+ ground state with a singlet–triplet gap of −5.2 kcal/mol rather than a cyclic 1A1 state (6.0 kcal/mol above the linear). Al2Na− has a triangular 3B1 ground state and a singlet–triplet gap of 6.9 kcal/mol. We obtained IEa(Al2Na) = 5.3 ± 0.2 eV and EAa(Al2Na) = 1.3 ± 0.2 eV.