Prediction of a Non-Valence Temporary Anion State of (NaCl)2

The equation-of-motion coupled cluster method is used to characterize the low-lying anion states of (NaCl)2 in its rhombic structure. This species is known to possess a non-valence bound anion of Ag symmetry. Our calculations also demonstrate that it has a non-valence temporary anion of B2u symmetry, about 14 meV above threshold. The potential energy curves of the two anion states and of the ground state of the neutral molecule are reported as a function of distortion along the symmetric stretch normal coordinate. Implications for experimental detection of the temporary anion state are discussed. The sensitivity of the results to the inclusion of high-order correlation effects and of core correlation is examined.