As one of the most important catalysts in polyethylene industry,Phillips catalyst(CrO_x/SiO_2)was quite unique for its activation by ethylene monomer without using any activator like alkyl-aluminium or MAO.In this wor...As one of the most important catalysts in polyethylene industry,Phillips catalyst(CrO_x/SiO_2)was quite unique for its activation by ethylene monomer without using any activator like alkyl-aluminium or MAO.In this work,the density functional theory(DFT)calculation combined with paired interacting orbitals(PIO)method was applied for the theoretical studies on coordination reaction mechanism between ethylene monomer and two model catalysts namely Cr(Ⅱ)(OH)_2(M1) and silsesquioxane-supported Cr(Ⅱ)(M2)as surfac...展开更多
Analysis of various mass formulas related to neutron-proton correlations in atomic nuclei is carried out.Using the example of the N =Z chain it is shown that for self-adjoint nuclei various formulas proposed in litera...Analysis of various mass formulas related to neutron-proton correlations in atomic nuclei is carried out.Using the example of the N =Z chain it is shown that for self-adjoint nuclei various formulas proposed in literature for estimating the np pairing energy lead to similar results. Significant differences between the calculation methods arise when nuclei with N = Z are considered, which allows to reveal the complexity of neutron-proton correlations in different types of atomic nuclei and to make assumptions on the correspondence of the mass relation to the real effect of np pairing. The Shell Model parametrization of the binding energy makes it possible to draw additional conclusions on the structure of mass formulas and their relationship.展开更多
Abstract： Various estimates of the even-odd effect of the mass shell of atomic nuclei are considered. Based on the experimental mass values of the Ca, Sn, and Pb isotopes, the dependence of the energy gap on the neut...Abstract： Various estimates of the even-odd effect of the mass shell of atomic nuclei are considered. Based on the experimental mass values of the Ca, Sn, and Pb isotopes, the dependence of the energy gap on the neutron number is traced and the relationship of this characteristic to the properties of external neutron subshells is shown. In nuclei with closed proton shells, effects directly related to neutron pairing and effects of nucleon shells are discussed.展开更多
The microscopic mechanism of nine experimentally observed bands in ^178W is investigated using the particle-number conserving method of the cranked shell model with monopole and quadrupole paring interactions. The exp...The microscopic mechanism of nine experimentally observed bands in ^178W is investigated using the particle-number conserving method of the cranked shell model with monopole and quadrupole paring interactions. The experimental results, including the moments of inertia and angular momentum alignments of nine bands in ^178W, are reproduced well by the particle-number conserving calculations, in which no free parameter is involved. Calculations demonstrate that occurrence of sharp backbending comes mainly from the contribution of high-j intruder orbitals vi13/2 or πh11/2 and their interference effect with orbitals near the Fermi surface. Theω variation of the occupation probability of each cranked orbital and the contribution to moment of inertia from each cranked orbital are analyzed.展开更多
基金the National Natural Science Foundation of China(No.20744004 and No.20774025).
文摘As one of the most important catalysts in polyethylene industry,Phillips catalyst(CrO_x/SiO_2)was quite unique for its activation by ethylene monomer without using any activator like alkyl-aluminium or MAO.In this work,the density functional theory(DFT)calculation combined with paired interacting orbitals(PIO)method was applied for the theoretical studies on coordination reaction mechanism between ethylene monomer and two model catalysts namely Cr(Ⅱ)(OH)_2(M1) and silsesquioxane-supported Cr(Ⅱ)(M2)as surfac...
基金Supported by Foundation for the Advancement of Theoretical Physics and Mathematics BASIS
文摘Analysis of various mass formulas related to neutron-proton correlations in atomic nuclei is carried out.Using the example of the N =Z chain it is shown that for self-adjoint nuclei various formulas proposed in literature for estimating the np pairing energy lead to similar results. Significant differences between the calculation methods arise when nuclei with N = Z are considered, which allows to reveal the complexity of neutron-proton correlations in different types of atomic nuclei and to make assumptions on the correspondence of the mass relation to the real effect of np pairing. The Shell Model parametrization of the binding energy makes it possible to draw additional conclusions on the structure of mass formulas and their relationship.
文摘Abstract： Various estimates of the even-odd effect of the mass shell of atomic nuclei are considered. Based on the experimental mass values of the Ca, Sn, and Pb isotopes, the dependence of the energy gap on the neutron number is traced and the relationship of this characteristic to the properties of external neutron subshells is shown. In nuclei with closed proton shells, effects directly related to neutron pairing and effects of nucleon shells are discussed.
基金National Natural Science Foundation of China under Grant No.10675006
文摘The microscopic mechanism of nine experimentally observed bands in ^178W is investigated using the particle-number conserving method of the cranked shell model with monopole and quadrupole paring interactions. The experimental results, including the moments of inertia and angular momentum alignments of nine bands in ^178W, are reproduced well by the particle-number conserving calculations, in which no free parameter is involved. Calculations demonstrate that occurrence of sharp backbending comes mainly from the contribution of high-j intruder orbitals vi13/2 or πh11/2 and their interference effect with orbitals near the Fermi surface. Theω variation of the occupation probability of each cranked orbital and the contribution to moment of inertia from each cranked orbital are analyzed.
