Spin Polarization Effect And Structures For The Transition Elements Molecules

Currently it is a major research subject to analyze the molecular structures of the transition elements, especially those transition elements in the 4th and 5th periods. And it is generally known that the multiplicity of ground state of diatomics for light elements is usually comparatively low, for example, 2s+1=1 4, which is because of the interaction of electronic configuration, particularly, the effect of electron pairing. However, the recent work indicates this is not the case for heavy elements. For example, for molecules Pu_n (n=2,3,4), the ground state of plutonium Pu is ⁷F_g with 6 of unpaired electrons, the unpaired electrons for Pu₂ , Pu₃ and Pu₄ will be 12, 18 and 24 ones, respectively, the possible multiplicities will be 2s+1=1, 3, 5, 7, 9, 11, and 13 for Pu₂, 2s+1=1, 3, 5, 7, 9,11, 13, 15, 17, and 19 for Pu₃, 2s+1=1, 3, 5, 7, 9, 11, 13, 15, 17, 19, 21, 23, and 25 for Pu₄ . The energy will decrease with multiplicity, the most stable configurations are of the multiplicities of 13, 19, 25 for Pu₂ , Pu₃ and Pu₄ , respectively. It is similar for U clusters .What are the implications of this situation? It means that the electrons prefer parallel spin in Pu_n and U clusters. This sort of non-equilibrium for electron spin is called spin-polarization effect. One of the major current research subjects is the spin-polarization for the actinides element molecules. The potential functions of compounds about heavy elements are alsoone of many scientific workers interest.1187'1881. There is no body care about the spin-polarization effect of the transitional elements, so our intention is to seeing about all the diatomic molecules in transitional elements, it means all the diatomic molecule's spin-polarization effect in those transition elements in the 4th period, and all the diatomic molecule-configuration and spin-polarization effect in those transition elements in the 5th period.According to Atomic and Molecular Reaction Statics, and the Group Theoretical Derivation of Molecular Electronic States, the method of density functional theory (DFT) in quantum mechanics, and the theory of multi-body item expandedness of potential function . We have investigated the diatomic molecules in those transition elements in the 4th period, the molecule's structure of Ti2> V2-Ct2 - Mri2 > Fe2^ C02 and N12 systemically, we have obtained the character of the molecule's micro-structure, such as the molecular structure, the energy and the spectroscopic data. There is spin-polarization effect exists in these molecules. We also investigate the diatomic molecule in those transition elements in the 5th period, which are Y2 NZ^Nb2 >Mo2 >Tc2>Ru2^Rh2andPd2, we have obtained the structure and potential function of these molecules, so we could judge that there is spin-polarization effect exists in these molecule too. All these works provide some credible data for the further research-Spin pollution is the error in the unlimited ab initio calculation. It often comes about in the total energy because the wave function of the ground state mingles with the wave function in higher-energetic states. High spin pollution will influence the molecular structure and the analysis of distributed numbers of molecules, especially the densities of spin. It also influences the constringency, especially the MPn assignment. The spin pollution can be validated by comparing the total prospective value of spin and the value of calculation. In general, the result is acceptable if the error is not beyond 10%.ForTi2N V2^ Cr2 n Mn2 n Fe2^ Co2 and Ni2 molecules, As the multiplicity increases, the unpaired electrons increase gradually. That is, in Ti2> V2^ Cr2 -. Mn2 > Fe2N Co2 and Ni2 molecules, the greater the number of the unpairedelectrons is, the lower its energy will be —the state with the lowest energy is the stablest. This condition is known as spin polarization effect. Pairing of electrons may reduce the energy of the system. However, the commutative integral of spin parallel electrons is positive, which also leads to reduction of the energy of the system. It shows that, in the transition element molecules, the effect of spin parallel is larger than the effect of paired electrons. It is obviously related to the delocalization of electron d. Meanwhile, we find that the minimal energy values of all multiple states of respectively Ti2N "VV Cr2 s Mn2 s Vei> Co2andNi2 molecule are very close to each other. So other multiple states of that molecule easily are thought the ground state of it. According to our thorough calculations, shows that there exists spin polarization effect in Ti2^ V2-. Cr2 -. Mn2 -. Fe2^ C02 and Ni2 molecule, the diatomic molecule of transition metal elements. And for these molecules we can find that prospective values and the calculation values of total spin about other multiple states are absolutely the same respectively except that 1 multiple state does not come up in the optimum result. It shows that there is no spin pollution in the DFT calculations for transition elements molecules, and that the wave function of the ground state does not mingle with the wave function of higher energy state.We have used the same method dealt with the those transition elements in the 5th period, and we found part of those transition elements in the 5th period's molecules have spin-polarization effect.For long time, the molecular structure of B2H6 (diborane) is a important undecided question, the core is the configuration of the atomic nucleus. There are different opinions about E^H^ Sidgwick.N.V thought electronic pair are used to create boron-boron bond and four boron-hydrogen bonds ,and among boron atom and other two hydrogen atoms create single electronic bond. Dilthey.W has confirmed it's geometrical configuration is the configuration of like-ethylene molecule, and has substantiated it with spectrum and other physical evidence. Use the method of electronic diffraction to mensurate carefully, the size of this molecule has obtained. But, the debate has not finished, even now; some peoplestill have different opinions about this conclusion. Some thought the geometrical molecule-configuration of B2H6 is like-ethane type D3h or D3d, and some others thought the geometrical molecule-configuration of B2H6 is like-ethylene type D2d or D2h , and D2h contains two circumstances: three-dimensional D2h and planar D2h. then, so the geometrical molecule-configuration of B2H6 has five circumstances. We have used the Gaussian98's program, and the method of B3P86^ BP86. B3LYPn BLYP^ UI^ HF and LSD A, investigated each of these five circumstances carefully, and did the systemic calculation for the 1 multiple state and 3 multiple state in all the five possible circumstances. It's electronic configuration is lAg, the conclusion is: the geometrical molecule-configuration of B2H6 is conventional like-ethylene type D2h , it's configuration like picture 7.9, and it's energy is the lowest.