THEORETICAL-STUDY OF SMALL ALUMINUM PHOSPHIDE AND MAGNESIUM SULFIDE CLUSTERS

Electronic structures and stabilities of small Al(n)P(n) and Mg(n)S(n) clusters (n = 1-3) are explored by means of accurate quantum chemical calculations. The effects of polarization functions and electron correlation are included in these calculations. Ionic factors are clearly dominant for MgS clusters. Thus, both Mg2S2 and Mg3S3 have planar ground state geometries where charge alternation is utilized effectively. AlP clusters, on the other hand, behave intermediate between the ionic MgS clusters and the covalent Si clusters. Thus, while the ground state structures of Al2P2 and Al3P3 are both analogous to those of the isoelectronic silicon clusters Si4 and Si6, other low-lying minima which are similar to those of MgS clusters are also present. The hybridization and bonding in the different structures are discussed.