Ab initio pseudopotential study of M2As- and M2Br+ (M = Cu, Ag, Au)

The equilibrium geometries and the vibration frequencies of M2As- and M2Br+ (M = Cu, Ag, Au) are calculated at the Hartree-Fock (HF) and the second-order Moller-Plesset (MP2) levels with pseudopotentials. The calculated results indicate that the species have a bent structure (C-2 upsilon) The electron correlation corrections on the geometrical structure are investigated at the MP2 level, the bond angles are reduced by 10 degrees-20 degrees for considered species. The electron correlation effects on the geometry of the Au2As- are studied particularly at MP2, MP3, MP4, CCSD and CCSD(T) levels. Comparing the species containing Ag and Au, the relativistic effects slightly short the bond lengths of the species. The bonding possibility of the Au2As- is predicted. (C) 2000 John Wiley & Sons, Inc.