Theoretical Studies On The Structures And Properties Of Neptunium And Protactinium Complexes

As the fast development of global economy,the human demand for energy consumption and increasing Therefore,the energy problem is the human society survival and the development of an eternal theme And nuclear power as a new type of efficient energy,more and more get people’s attention Nuclear waste treatment and improve the utilization rate of nuclear fuel,however,has become the current nuclear energy can be the key to sustainable development problems.Actinide elements and their compounds is the main source of radioactive material in nuclear waste,the long life of radioactive elements can produce serious harm to human and environment neptunium(Np)element is one of the main radioactive elements in the nuclear waste,and magnesium(Pa)as thorium-uranium fuel mix is an important element in the circulation system.Therefore,in order to further explore more reasonable effectively of Np element and its compounds are dealt with the new way to radioactive waste,and explore the Pa elements in thorium-uranium fuel mix how to improve the recycling of nuclear fuel in the reactor,it is necessary to Np,Pa actinide compounds,such as the nature of the in-depth research.In this paper,B3 LYP hybridized density functional and generalized gradient approximation GGA:PBE are used to exchange correlation functional methods in DFT.Gauss03 software was used in the study of Np,and the structure and chemical bond properties of Np compounds were investigated by using the gaussian base group and the relativistic effective core potential(RECP).The Pa study uses the Amsterdam density functional(ADF2017)software and uses the all-electronic Slater base group to deal with the relativistic effect with the zero-order regular approximation(ZORA).The system has studied several common concrete works as follows:1.Neptunium ions(Np4+)was studied with different number of nitrate ion complexes formed by the union of Np(NO3)n q(n = 1 ~ 6,q = 2 ~ + 3)the structure and properties of the research results show that Np(NO3)n q complexes in the form of the combination of the double toothed combine to stabilize the second,in general,bond length,bond energy,damage the key difficulties,material is more stable.And,The distance between Np4+and 2(NO3-)is the shortest distance between N and Oeq atoms in NO3-.But according to the calculation of the binding energy,Np4+ and NO3-tend to combine to form stable complexes of Np(NO3)4;Finally,stable structures Np(NO3)4 IR spectra of complexes,and compared with the experimental data,the results conform to the better.2.Pa ion(Pa5+)was studied in HF solution in the stable structure and chemical properties.By the theoretical calculation of reaction energy and free energy get Pa5+ can combine with 8F and Pa O3+ can be combined with 5F–.By using QTAIM method and ELF method,the bonding of Pa F83-、 Pa(H2O)85+、Pa OF52-and Pa O(H2O)53+ compounds was calculated.The results show that there is a certain covalent relationship between Pa atom and F atom and O atoms in H2 O.The results of the Bond order、density of state and X-ray near-edge absorption spectra analysis show that because Pa 5f and 6d orbital overlaps with the 2p orbital of F or O atoms,there is a certain covalence between the Pa atom and the F atom or O atoms in H2 O.and The covalency between Pa atom and F atom is stronger than that of O atoms.