Theoretical Study On Neutral, Cationic And Anionic Arsenic Clusters As_n(n=2-15), As_n~+(n=2-15) And As_n~-(n=2-15)

The dissertation is devoted to the theoretical study on neutral arsenic clusters As_n (n=2-15),cationic arsenic clusters As_n~+(n=2-15) and cationic arsenic clusters As_n~-(n=2-15).All kinds of possible models are explored employing B3LYP/6-31G* combining Molecular Graphics and Molecular Mechanics.To ascertain the lowest-lying structures,the single point energies are calculated at the level B3LYP/6-311+G*.In the analysis of valence bond structures,we summarize the structural rules.And the parity alternation in the time-flight mass spectra and photoelectron spectroscopy is interpreted based on the compare of the Energy Difference,the Incremental Binding Energies,Ionization Potentials and Electron Affinities.Main results and conclusions could be summarized as follows:1.As_n(n=2-15) Arsenic neutral clustersWe ascertain the ground state of neutral arsenic clusters As_n(n=2-15) through the theoretical computation.Referring to the John-Teller effect,we discuss its impact on the structure of the cluster.Through the Energy Differences and Incremental Binding Energy we find that the neutral arsenic clusters with even n are more stable than those with odd n.2.As_n~+(n=2-15) cationic clustersThe stabilities of the As_n~+(n=2-15) cationic clusters exhibit obvious even/odd alternations.The lowest-lying structures are established by theoretical computation. Referring to the John-Teller effect,we discuss its impact on the structure of the cluster. The clusters with "odd-n" are more stable than those with "even-n",which can be concluded from the Energy Differences,the Incremental Binding Energies and the Energy Differences.The results of the calculations are in good agreement with experimental data.3.As_n~-(n=2-15) cationic clustersStructural and electronic properties of As_n~- anionic clusters have been investigated using the B3LYP-DFT method in the ranges of n=2-15.All the structures meet the requirements of The Jahn-Teller Theorem.The clusters with "odd-n" are more stable than those with "even-n".The odd/even alternation trend can be explained according to the Energy Differences,Incremental Binding Energies,and Adiabatic Electron Affinities.The results of calculation are in good agreement with the experimental phenomena observed in mass spectrometric studies.Knowledge acquired in this dissertation can provide helpful information for the synthesis of large arsenic clusters.