The possible exotic nuclear properties in the neutron-rich Ca,Ni,Zr,and Sn isotopes are examined with the continuum Skyrme Hartree-Fock-Bogoliubov theory in the framework of the Green’s function method.The pairing co...The possible exotic nuclear properties in the neutron-rich Ca,Ni,Zr,and Sn isotopes are examined with the continuum Skyrme Hartree-Fock-Bogoliubov theory in the framework of the Green’s function method.The pairing correlation,the couplings with the continuum,and the blocking effects for the unpaired nucleon in odd-A nuclei are properly treated.The Skyrme interaction SLy4 is adopted for the ph channel and the density-dependentinteraction is adopted for the pp chan-nel,which well reproduce the experimental two-neutron separation energies S_(2n)and one-neutron separation energies Sn.It is found that the criterion S_(n)>0 predicts a neutron drip line with neutron numbers much smaller than those for S_(2n)>0.Owing to the unpaired odd neutron,the neutron pairing energies−E_(pair)in odd-A nuclei are much lower than those in the neighbor-ing even-even nuclei.By investigating the single-particle structures,the possible halo structures in the neutron-rich Ca,Ni,and Sn isotopes are predicted,where sharp increases in the root-mean-square(rms)radii with significant deviations from the traditional rA^(1∕3)rule and diffuse spatial density distributions are observed.Analyzing the contributions of various partial waves to the total neutron densityρlj(r)∕ρ(r)reveals that the orbitals located around the Fermi surface-particularly those with small angular momenta-significantly affect the extended nuclear density and large rms radii.The number of neutrons Nλ(N_(0))occupying above the Fermi surfacen(continuum threshold)is discussed,whose evolution as a function of the mass number A in each isotope is consistent with that of the pairing energy,supporting the key role of the pairing correlation in halo phenomena.展开更多
The Cauchy problem of the generalized Kuramoto-Sivashinsky equation in multidimensions(n ≥ 3) is considered. Based on Green's function method, some ingenious energy estimates are given. Then the global existence ...The Cauchy problem of the generalized Kuramoto-Sivashinsky equation in multidimensions(n ≥ 3) is considered. Based on Green's function method, some ingenious energy estimates are given. Then the global existence and pointwise convergence rates of the classical solutions are established. Furthermore, the L^p convergence rate of the solution is obtained.展开更多
The idea of replacing traditional silicon-based electronic components with the ones assembled by organic molecules to further scale down the electric circuits has been attracting extensive research focuses.Among the m...The idea of replacing traditional silicon-based electronic components with the ones assembled by organic molecules to further scale down the electric circuits has been attracting extensive research focuses.Among the molecularly assembled components,the design of molecular logic gates with simple structure and high Boolean computing speed remains a great challenge.Here,by using the state-of-the-art nonequilibrium Green’s function theory in conjugation with first-principles method,the spin transport properties of single-molecule junctions comprised of two serially connected transition metal dibenzotetraaza[14]annulenes(TM(DBTAA),TM=Fe,Co)sandwiched between two single-walled carbon nanotube electrodes are theoretically investigated.The numerical results show a close dependence of the spin-resolved current-voltage characteristics on spin configurations between the left and right molecular kernels and the kind of TM atom in TM(DBTAA)molecule.By taking advantage of spin degree of freedom of electrons,NOR or XNOR Boolean logic gates can be realized in Fe(DBTAA)and Co(DBTAA)junctions depending on the definitions of input and output signals.This work proposes a new kind of molecular logic gates and hence is helpful for further miniaturization of the electric circuits.展开更多
Using the nonequilibrium Keldysh Green＇s function technique, the Fano effect of a parallel-coupled triple Rashba quantum dot system is investigated. The conductance as a function of electron energy is numerically cal...Using the nonequilibrium Keldysh Green＇s function technique, the Fano effect of a parallel-coupled triple Rashba quantum dot system is investigated. The conductance as a function of electron energy is numerically calculated. Compared with the case of a parallel-coupled double quantum dot system, two additional Fano resonance peaks occur in the conductance spectrum. By adjusting the structural parameters, the two Fano resonance peaks may change into the resoaance peaks. In addition, the influence of Rashba spin-orbit interaction on the conductance is studied.展开更多
Using the nonequilibrium Green＇s function technique,electron transport through a laterally coupled vertical triple quantum dot is investigated.The conductance as a function of electron energy is numerically calculate...Using the nonequilibrium Green＇s function technique,electron transport through a laterally coupled vertical triple quantum dot is investigated.The conductance as a function of electron energy is numerically calculated.The evolution of the conductance strongly depends on the configuration of dot levels and interdot coupling strengths.展开更多
Based on density functional theory and non-equilibrium Green’s function method,we studied noncollinear magnetism and spin transport in a 180°domain wall made of zigzag graphene nanoribbon(ZGNR)with different non...Based on density functional theory and non-equilibrium Green’s function method,we studied noncollinear magnetism and spin transport in a 180°domain wall made of zigzag graphene nanoribbon(ZGNR)with different noncollinear magnetic profiles on the top and bottom edges.Our results show that a helical domain wall on the top(bottom)edge and an abrupt domain wall on the bottom(top)edge can survive in the ZGNR.This indicates that such characteristic magnetization distribution can be obtained by some means,e.g.,the introduction of impurity on one edge.Compared to a wide ZGNR,a narrow ZGNR presents obvious coupling between the two edges which changes the magnetization and transmission greatly.As for the above-mentioned distinct magnetic profile,the spin transport is blocked in the abrupt domain wall due to strong spin flip scattering while remains unaffected in the helical domain wall due to the spin mixing effect.We deduce a formula of the transmission for various magnetic profiles of the ZGNRs.A new result based on this formula is that the transmission at the Fermi level can be zero,one,and two by tuning the edge magnetization.Our results provide insights into the noncollinear spin transport of the ZGNR-based devices.展开更多
In this study, the thermoelectric properties of pyrene molecule doped with boron and nitrogen atom at different sites of molecule are investigated using density functional theory and none-equilibrium Greens function f...In this study, the thermoelectric properties of pyrene molecule doped with boron and nitrogen atom at different sites of molecule are investigated using density functional theory and none-equilibrium Greens function formalism in the linear response regime. Our calculations show that when the impurities are added to the edge of the molecule, the anti-resonant peaks will appear in the transmission diagram in the vicinity of the Fermi energy level. So it increases the thermoelectric figure of merit of the system in comparison with the one that the impurity is located in the center of molecule. Additionally, the seebeck coefficient signs are not the same among the B, N, and N ＆ B doped devices, indicating that the types of the carriers can be changed with different types of doping.展开更多
Very recently,experimental evidence showed that the hydrogen is retained in dithiol-terminated single-molecule junction under the widely adopted preparation conditions,which is in contrast to the accepted view[Nat.Che...Very recently,experimental evidence showed that the hydrogen is retained in dithiol-terminated single-molecule junction under the widely adopted preparation conditions,which is in contrast to the accepted view[Nat.Chem.11351(2019)].However,the hydrogen is generally assumed to be lost in the previous physical models of single-molecule junctions.Whether the retention of the hydrogen at the gold-sulfur interface exerts a significant effect on the theoretical prediction of spin transport properties is an open question.Therefore,here in this paper we carry out a comparative study of spin transport in M-tetraphenylporphyrin-based(M=V,Cr,Mn,Fe,and Co;M-TPP)single-molecule junction through Au-SR and Au-S(H)R bondings.The results show that the hydrogen at the gold-sulfur interface may dramatically affect the spin-filtering efficiency of M-TPP-based single-molecule junction,depending on the type of transition metal ions embedded into porphyrin ring.Moreover,we find that for the Co-TPP-based molecular junction,the hydrogen at the gold-sulfur interface has no obvious effect on transmission at the Fermi level,but it has a significant effect on the spin-dependent transmission dip induced by the quantum interference on the occupied side.Thus the fate of hydrogen should be concerned in the physical model according to the actual preparation condition,which is important for our fundamental understanding of spin transport in the single-molecule junctions.Our work also provides guidance in how to experimentally identify the nature of gold-sulfur interface in the single-molecule junction with spin-polarized transport.展开更多
The structure of a heterojunction made up of an （8, 0） carbon nanotube and an （8, 0） boron nitride nanotube is achieved through geometry optimization implemented in the CASTEP package. Based on the optimized geome...The structure of a heterojunction made up of an （8, 0） carbon nanotube and an （8, 0） boron nitride nanotube is achieved through geometry optimization implemented in the CASTEP package. Based on the optimized geometry, the model of the heterojunction is established. Its transport properties are investigated by combining the nonequilibrium Green＇s function with density functional theory. Results show that both the lowest unoccupied molecular orbital and the highest occupied molecular orbital mainly locate on the carbon nanotube section. In the current-voltage characteristic of the heterojunction, a rectification feature is revealed.展开更多
In this article, the author studies the Cauchy problem of the damped wave equation with a nonlinear convection term in multi-dimensions. The author shows that a classical solution to the Cauchy problem exists globally...In this article, the author studies the Cauchy problem of the damped wave equation with a nonlinear convection term in multi-dimensions. The author shows that a classical solution to the Cauchy problem exists globally in time under smallness condition on the initial perturbation. Furthermore, the author obtains the L^p （2 ≤ p ≤ ∞） decay estimates of the solution.展开更多
The atomistic Green’s function method is improved to compute the polarization resolved phonon transport in a multiterminal system. Based on the recent developments in literature, the algorithm is simplified. The comp...The atomistic Green’s function method is improved to compute the polarization resolved phonon transport in a multiterminal system. Based on the recent developments in literature, the algorithm is simplified. The complex phonon band structure of a semi-infinite periodic terminal is obtained by the generalized eigenvalue equation. Then both the surface Green’s function and phonon group velocity in the terminal are determined from the wave modes propagating away from the scattering region along the terminal. With these key ingredients, the individual phonon mode transmittance between the terminals can be calculated. The feasibility and validity of the method are demonstrated by the chain example compared with the wave packet method, and an example of graphene nanojunction with three terminals.展开更多
In this work,the electronic transport properties of Z-shaped silicene nanoribbon（ZsSiNR） structure are investigated.The calculations are based on the tight-binding model and Green＇s function method in Landauer-Biit...In this work,the electronic transport properties of Z-shaped silicene nanoribbon（ZsSiNR） structure are investigated.The calculations are based on the tight-binding model and Green＇s function method in Landauer-Biittiker formalism,in which the electronic density of states（DOS）,transmission probability,and current-voltage characteristics of the system are calculated,numerically.It is shown that the geometry of the ZsSiNR structure can play an important role to control the electron transport through the system.It is observed that the intensity of electron localization at the edges of the ZsSiNR decreases with the increase of the spin-orbit interaction（SOI） strength.Also,the semiconductor to metallic transition occurs by increasing the SOI strength.The present theoretical results may be useful to design silicene-based devices in nanoelectronics.展开更多
基金the National Natural Science Foundation of China(No.U2032141)the Open Project of Guangxi Key Laboratory of Nuclear Physics and Nuclear Technology(No.NLK2022-02)+4 种基金the Central Government Guidance Funds for Local Scientific and Technological Development,China(Guike ZY22096024)the Natural Science Foundation of Henan Province(No.202300410479)the Guizhou Provincial Science and Technology Projects(No.ZK[2022]203)the Foundation of Fundamental Research for Young Teachers of Zhengzhou University(No.JC202041041)the Physics Research and Development Program of Zhengzhou University(No.32410217).
文摘The possible exotic nuclear properties in the neutron-rich Ca,Ni,Zr,and Sn isotopes are examined with the continuum Skyrme Hartree-Fock-Bogoliubov theory in the framework of the Green’s function method.The pairing correlation,the couplings with the continuum,and the blocking effects for the unpaired nucleon in odd-A nuclei are properly treated.The Skyrme interaction SLy4 is adopted for the ph channel and the density-dependentinteraction is adopted for the pp chan-nel,which well reproduce the experimental two-neutron separation energies S_(2n)and one-neutron separation energies Sn.It is found that the criterion S_(n)>0 predicts a neutron drip line with neutron numbers much smaller than those for S_(2n)>0.Owing to the unpaired odd neutron,the neutron pairing energies−E_(pair)in odd-A nuclei are much lower than those in the neighbor-ing even-even nuclei.By investigating the single-particle structures,the possible halo structures in the neutron-rich Ca,Ni,and Sn isotopes are predicted,where sharp increases in the root-mean-square(rms)radii with significant deviations from the traditional rA^(1∕3)rule and diffuse spatial density distributions are observed.Analyzing the contributions of various partial waves to the total neutron densityρlj(r)∕ρ(r)reveals that the orbitals located around the Fermi surface-particularly those with small angular momenta-significantly affect the extended nuclear density and large rms radii.The number of neutrons Nλ(N_(0))occupying above the Fermi surfacen(continuum threshold)is discussed,whose evolution as a function of the mass number A in each isotope is consistent with that of the pairing energy,supporting the key role of the pairing correlation in halo phenomena.
基金supported by the National Natural Science Foundation of China(11271141)Chongqing Science&Technology Commission(cstc2018jcyjAX0787)
文摘The Cauchy problem of the generalized Kuramoto-Sivashinsky equation in multidimensions(n ≥ 3) is considered. Based on Green's function method, some ingenious energy estimates are given. Then the global existence and pointwise convergence rates of the classical solutions are established. Furthermore, the L^p convergence rate of the solution is obtained.
基金National Natural Science Foundation of China(Grant Nos.11874242,21933002,and 11704230)China Postdoctoral Science Foundation(Grant No.2017M612321)the Taishan Scholar Project of Shandong Province of China.
文摘The idea of replacing traditional silicon-based electronic components with the ones assembled by organic molecules to further scale down the electric circuits has been attracting extensive research focuses.Among the molecularly assembled components,the design of molecular logic gates with simple structure and high Boolean computing speed remains a great challenge.Here,by using the state-of-the-art nonequilibrium Green’s function theory in conjugation with first-principles method,the spin transport properties of single-molecule junctions comprised of two serially connected transition metal dibenzotetraaza[14]annulenes(TM(DBTAA),TM=Fe,Co)sandwiched between two single-walled carbon nanotube electrodes are theoretically investigated.The numerical results show a close dependence of the spin-resolved current-voltage characteristics on spin configurations between the left and right molecular kernels and the kind of TM atom in TM(DBTAA)molecule.By taking advantage of spin degree of freedom of electrons,NOR or XNOR Boolean logic gates can be realized in Fe(DBTAA)and Co(DBTAA)junctions depending on the definitions of input and output signals.This work proposes a new kind of molecular logic gates and hence is helpful for further miniaturization of the electric circuits.
基金supported by the Youth Foundation of Heilongjiang Province,China(Grant No.QC2009C41)the Heilongjiang Provincial Natural Science Foundation,China(Grant No.F200939)
文摘Using the nonequilibrium Keldysh Green＇s function technique, the Fano effect of a parallel-coupled triple Rashba quantum dot system is investigated. The conductance as a function of electron energy is numerically calculated. Compared with the case of a parallel-coupled double quantum dot system, two additional Fano resonance peaks occur in the conductance spectrum. By adjusting the structural parameters, the two Fano resonance peaks may change into the resoaance peaks. In addition, the influence of Rashba spin-orbit interaction on the conductance is studied.
基金Project supported by the Youth Foundation of Heilongjiang Province,China (Grant No. QC2009C41)the Heilongjiang Provincial Natural Science Foundation,China (Grant No. F200939)
文摘Using the nonequilibrium Green＇s function technique,electron transport through a laterally coupled vertical triple quantum dot is investigated.The conductance as a function of electron energy is numerically calculated.The evolution of the conductance strongly depends on the configuration of dot levels and interdot coupling strengths.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.NSFC11804158,NSFC61974067,NSFC91750112,and NSFC11947101)。
文摘Based on density functional theory and non-equilibrium Green’s function method,we studied noncollinear magnetism and spin transport in a 180°domain wall made of zigzag graphene nanoribbon(ZGNR)with different noncollinear magnetic profiles on the top and bottom edges.Our results show that a helical domain wall on the top(bottom)edge and an abrupt domain wall on the bottom(top)edge can survive in the ZGNR.This indicates that such characteristic magnetization distribution can be obtained by some means,e.g.,the introduction of impurity on one edge.Compared to a wide ZGNR,a narrow ZGNR presents obvious coupling between the two edges which changes the magnetization and transmission greatly.As for the above-mentioned distinct magnetic profile,the spin transport is blocked in the abrupt domain wall due to strong spin flip scattering while remains unaffected in the helical domain wall due to the spin mixing effect.We deduce a formula of the transmission for various magnetic profiles of the ZGNRs.A new result based on this formula is that the transmission at the Fermi level can be zero,one,and two by tuning the edge magnetization.Our results provide insights into the noncollinear spin transport of the ZGNR-based devices.
文摘In this study, the thermoelectric properties of pyrene molecule doped with boron and nitrogen atom at different sites of molecule are investigated using density functional theory and none-equilibrium Greens function formalism in the linear response regime. Our calculations show that when the impurities are added to the edge of the molecule, the anti-resonant peaks will appear in the transmission diagram in the vicinity of the Fermi energy level. So it increases the thermoelectric figure of merit of the system in comparison with the one that the impurity is located in the center of molecule. Additionally, the seebeck coefficient signs are not the same among the B, N, and N ＆ B doped devices, indicating that the types of the carriers can be changed with different types of doping.
基金the National Natural Science Foundation of China(Grant Nos.11674092,11804093,and 61764005)the Natural Science Foundation of Hunan Province,China(Grant No.2019JJ40006)+2 种基金the Scientific Research Fund of the Education Department of Hunan Province,China(Grant No.18B368)the Science and Technology Development Plan Project of Hengyang City,China(Grant No.2018KJ121)the Science and Technology Plan Project of Hunan Province,China(Grant No.2016TP1020).
文摘Very recently,experimental evidence showed that the hydrogen is retained in dithiol-terminated single-molecule junction under the widely adopted preparation conditions,which is in contrast to the accepted view[Nat.Chem.11351(2019)].However,the hydrogen is generally assumed to be lost in the previous physical models of single-molecule junctions.Whether the retention of the hydrogen at the gold-sulfur interface exerts a significant effect on the theoretical prediction of spin transport properties is an open question.Therefore,here in this paper we carry out a comparative study of spin transport in M-tetraphenylporphyrin-based(M=V,Cr,Mn,Fe,and Co;M-TPP)single-molecule junction through Au-SR and Au-S(H)R bondings.The results show that the hydrogen at the gold-sulfur interface may dramatically affect the spin-filtering efficiency of M-TPP-based single-molecule junction,depending on the type of transition metal ions embedded into porphyrin ring.Moreover,we find that for the Co-TPP-based molecular junction,the hydrogen at the gold-sulfur interface has no obvious effect on transmission at the Fermi level,but it has a significant effect on the spin-dependent transmission dip induced by the quantum interference on the occupied side.Thus the fate of hydrogen should be concerned in the physical model according to the actual preparation condition,which is important for our fundamental understanding of spin transport in the single-molecule junctions.Our work also provides guidance in how to experimentally identify the nature of gold-sulfur interface in the single-molecule junction with spin-polarized transport.
基金Project supported by the Chinese Defence Advance Research Program of Science and Technology,China (GrantNo. 9140A08060407DZ0103)
文摘The structure of a heterojunction made up of an （8, 0） carbon nanotube and an （8, 0） boron nitride nanotube is achieved through geometry optimization implemented in the CASTEP package. Based on the optimized geometry, the model of the heterojunction is established. Its transport properties are investigated by combining the nonequilibrium Green＇s function with density functional theory. Results show that both the lowest unoccupied molecular orbital and the highest occupied molecular orbital mainly locate on the carbon nanotube section. In the current-voltage characteristic of the heterojunction, a rectification feature is revealed.
基金supported by Shanghai Municipal Natural Science Foundation 09ZR1413500National Natural Science Foundation of China 11071162
文摘In this article, the author studies the Cauchy problem of the damped wave equation with a nonlinear convection term in multi-dimensions. The author shows that a classical solution to the Cauchy problem exists globally in time under smallness condition on the initial perturbation. Furthermore, the author obtains the L^p （2 ≤ p ≤ ∞） decay estimates of the solution.
基金Project supported by the National Natural Science Foundation of China(Grant No.51376094)Jiangsu Overseas Visiting Scholar Program for University Prominent Young&Middle-aged Teachers and Presidents,China
文摘The atomistic Green’s function method is improved to compute the polarization resolved phonon transport in a multiterminal system. Based on the recent developments in literature, the algorithm is simplified. The complex phonon band structure of a semi-infinite periodic terminal is obtained by the generalized eigenvalue equation. Then both the surface Green’s function and phonon group velocity in the terminal are determined from the wave modes propagating away from the scattering region along the terminal. With these key ingredients, the individual phonon mode transmittance between the terminals can be calculated. The feasibility and validity of the method are demonstrated by the chain example compared with the wave packet method, and an example of graphene nanojunction with three terminals.
基金Project supported by the Sari Branch,Islamic Azad University,Iran Grant No.1-24850
文摘In this work,the electronic transport properties of Z-shaped silicene nanoribbon（ZsSiNR） structure are investigated.The calculations are based on the tight-binding model and Green＇s function method in Landauer-Biittiker formalism,in which the electronic density of states（DOS）,transmission probability,and current-voltage characteristics of the system are calculated,numerically.It is shown that the geometry of the ZsSiNR structure can play an important role to control the electron transport through the system.It is observed that the intensity of electron localization at the edges of the ZsSiNR decreases with the increase of the spin-orbit interaction（SOI） strength.Also,the semiconductor to metallic transition occurs by increasing the SOI strength.The present theoretical results may be useful to design silicene-based devices in nanoelectronics.
