We designed and optimized a large number of the isomers of Si12＋ at the level of density functional theory （DFT）-B3LYP/6-311＋＋G（d） using the Gaussian 03 software package. An unambiguous structure of the Si12＋ cluster is presented, whose IR spectrum agrees well with the experiment result. The most stable geometric structures of Gen＋（n=2―15） clusters were determined by the all-electron PBE/DND method in DMol3 of the Material Studio Package, and compared with those of the corresponding Sin＋ geometries. Most structures of Gen＋ and Sin＋ are similar except the ones of those for n=9, 12, 13 and 14, and the pentagonal bipyramid motif and the tri-capped trigonal prism（TTP） motif often appear in the Sin＋ and Gen＋（n=7―15） structures（except for Si14＋）.
Al2-Al40 clusters were studied by means of the all-electron DFT method. The properties of the aluminum clusters including binding energy, the second difference in energy, HOMO-LUMO gap, especially fragmentation energies and ionization potentials, were analyzed. The main products from the dissociations of aluminum cluster ions are shown to be Al ＋ Al^＋n-1 for the larger clusters, and Al^＋ ＋Aln-1 for the smaller ones. And, the calculated ionization potentials are consistent with the experiment data.
The N2H＋O potential energy profile was studied at the CCSD（T）/6-311G＋＋（df,p）//MP2/6-311G（d,p） level. Reactions associated with four intermediates（cis-HNNO, trans-HNNO, NNHO, and NNOH） were investigated. The results indicate that N2H＋O reaction toward H＋N2O is more favored than that toward N2＋OH, consistent with previous experimental studies. The pathways for the two reactions are found to go through cis-HNNO, transition state, and finally to the products. The N2H＋O→NH＋NO reaction was studied in detail. Product NO in such a reaction is likely to occur via cis-HNNO, followed by trans-HNNO, and finally dissociates into NH＋NO. These results suggest that N2H＋O→NH＋NO is an important channel in NO production.
The properties of Pbn（n=2―30） clusters including binding energies,second differences in energy,and HOMO-LUMO gaps,especially fragmentation energies and ionization potentials,have been studied by ab initio calculation.The main fragmentation products of Pbn＋ are shown to be Pb＋Pbn-1＋ for n≤14 and two small cluster fragments for larger ones with n14.The Pb13＋ appears frequently as the products in the fragmentations of large clusters.Also,the calculated ionization potentials of the clusters are consistent with the experiment data.
LI Xiao-pingZHANG WeiLUE Wen-caiWANG Cai-zhuangHO Kai-ming
