A Theoretical Study On The Structures, Properties Of Pt_n Clusters And The Adsorption Of Gas Molecule On Them Under External Electric Field

Clusters are the borderland between the macroscopic solid state and atoms, andclusters are the agglomerates of a few to a few thousand atoms with relative stability,because of their abnormal physical and chemical behavior, clusters have been widelyapplied in material physical chemistry science、nanotechnology and so on. The rapiddevelopment in density functional theory and computer science make theoreticalstudy on structures and properties of atom clusters come to reality. Platinum clustershave been received considerable attention during the past few years, the interestmainly originates from the remarkable physical and chemical properties andapplication as catalyst. However, its experimental synthesis rate is not high, it isdifficult to separate and the information of experiment is lack, so it is very importantof theoretical study on platinum clusters for experiments. In general, the adsorptionprocess is the key of chemical reactions on the surface of the cluster, so the adsorptionof small molecules on cluster has caused extensive concern of the researchers.Furthermore, it is well-known that an electric field F can effectively modify theproperties of low dimensional system, and affect the adsorption of gas molecules.In this work, we use Dmol3code that is the module of Materials Studio softwarepackage to calculate, which base on density functional theory.First, we calculate the bond length, the number of charge, binding energy, thehighest occupied orbital (HOMO), the lowest empty orbital (LUMO), energy Gap(HOMO, LUMO Gap) of Ptn(n=2-4) clusters、CO molecule and O2molecule underthe external electric field, and analyze the change rule of physical quantities along theexternal electric field. The result shows：the influence of positive、negative electricfield on the bond length, charge number and other physical quantities of Ptnclusters isdifferent and significant, with the increasing of atomic number, the binding energy ofplatinum clusters enlarge gradually. The bond length and atom charge of CO moleculegradually decrease with the increase of the electric field. The bond length and energygap of O2molecule along the increasing electric field intensity, the atom charge of O2molecule increasing with the increase of the electric field.Then we research Ptn(n=1-4) clusters adsorption CO molecule、O2moleculerespectively under external electric field, analyze the changing of binding energy and energy gap along the external electric field, the change of the bond length of gasmolecule in system in or out of electric field. The influence of Ptnclusters andexternal electric field on CO、O2molecules，and the influence of increasing platinumnumber of clusters.