Theoretical Chemistry Studies On CaMn_mO_n Clusters And Their Ions

CaMnmOnis a kind of clusters that has interesting properties, and is potential candidatefor water oxidation. The study on CaMnmOnclusters will give spark on understanding thecluster structure, catalysis and adsorption process. To understanding the basic problems, it isnecessary to carry out deep studies on the electronic structure and chemical properties ofCaMnmOnclusters. In this thesis, the geometry, characteristics and chemical bonding nature ofthe CaMnmOn(m, n=1-4) clusters and their ions have been studied with quantum chemistrymethod combined with topological analysis of electronic density.In Chapter one, the application of clusters and metal oxides clusters in syntheticchemistry, solid state physics, biology and materials science, as well as the researchimportance have been summarized briefly. Detailed analysis on the experimental andtheoretical research results on manganese molecular magnets, manganese oxide, calciumoxide and CaMnmOnclusters has been carried out.In Chapter two, the basic theory of quantum chemistry has been given, and also the basicidea of topological analysis of electronic density.In Chapter three,25kinds of density functional model chemistry were tested forCaMnmOnsystem based on the calculated results on MnO、MnO+、MnO-、CaO、CaO+、CaO-.The results show B3LYP/gen(cc-pvdz for Ca、Mn, aug-cc-pvdz for O) is most suitable for thesystem.In Chapter four, the possible electroni states of CaMnO、CaMnO2、CaMn2O、CaMn2O2have been optimized at B3LYP/(aug-cc-pvdz for O,cc-pvdz for Mn、Ca) level of theory. Byanlysing the different electronic states of each cluster, the ground state of the cluster isconfirmed. The results show that CaMnO、CaMnO2has a moment of5B, and CaMn2O、CaMn2O2have a moment of10B. The geometry structure of the four clusters are inapproximately planer.In Chapter five, the possible states of CaMn2O3、CaMn3O2、CaMn3O3、CaMn3O4、CaMn4O3、CaMn4O4have been optimized at B3LYP/3-21G(d). Aseries of electronic states ofeach cluster have been confirmed. The ground state of CaMn2O3、CaMn4O3、CaMn4O4have amoment of10B, and the ground state of CaMn3O2、CaMn3O3、CaMn3O4have a moment of5B。The geometry structure of ground state of CaMn2O3、CaMn3O2is close to planer. Thegeometry structure of ground state of CaMn3O3、CaMn3O4、CaMn4O3、CaMn4O4is in three dimension.In Chapter six, the anions and cations of CaMnmOn(m，n=1-4) have been optimized atB3LYP/(aug-cc-pvdz for O, cc-pvdz for Mn、Ca). Based on analyzing the ionization potential,electron affinity and binding energy, CaMn3O4is confirmed to be most stable, and CaMn3O4is mostly the basic unit in construting CaMnmOncluster. The atomic charge and atomic dipolemoment indicate water will be easily attacted to CaMnmOn. Topological properties of electrondensity of groud state of the mentioned clusters shows the chemical bonds in the cluster areionic.