Geometries and energies of small Gen(n= 2–6) clusters: an ab initio molecular orbital study

The molecular geometries and relative stabilities of various electronic configurations of Gen clusters (n= 2–6) have been investigated by means of ab initio calculations by employing an effective core potential for core electrons and a double zeta plus polarization functions basis set for valence electrons. The calculations have produced the following optimal configurations: Ge2(D∞h, 3Σ–g), Ge3(equilateral triangle, D3h3A′2), Ge4(planar rhombus D2h1Ag), Ge5(oblate distorted trigonal bipyramid, D3h1A′1), Ge6(edge-capped trigonal bipyramid, C2v1A1).Binding energies have been evaluated by single-point CISD(Q) calculations at the SCF optimal ground-state geometry of the clusters. The results are in qualitative agreement with experimental data. The comparison of Gen and Sin properties shows close similarity between Ge and Si.