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-or der Moller-Plesset (MP2) levels with pseudopotentials. The calculated resul ts indicate that the species have a bent structure (C-2 upsilon) The electr on correlation corrections on the geometrical structure are investigated at the MP2 level, the bond angles are reduced by 10 degrees-20 degrees for co nsidered species. The electron correlation effects on the geometry of the A u2As- are studied particularly at MP2, MP3, MP4, CCSD and CCSD(T) levels. C omparing the species containing Ag and Au, the relativistic effects slightl y short the bond lengths of the species. The bonding possibility of the Au2 As- is predicted. (C) 2000 John Wiley & Sons, Inc.