ELECTRON-AFFINITIES OF AG4 AND AU4

Electron affinities of Ag4 and Au4 as well as Ag3 and Au3 are computed using complete-active space multi-configuration self-consistent field (CAS MCSCF) followed by singles + doubles CI + Q (SDCI + Q) and multi-reference singles + doubles CI + Q (MRSDCI + Q) calculations which included up to 1.2 million configurations. Our computed electron affinities for the tetramers when scaled by a factor 1.3 and 1.35 for Ag4 and Au4, respectively, are in good agreement with the recent experimental values of Smalley and co-workers. The electron affinities of tetramers are found to be considerably smaller than trimers.