The dissipation phenomenon in the heavy-ion reaction at incident energy near the Fermi energy is studied by simulating the reaction ^129Xe＋^129Sn with the isospin-dependent quantum molecular dynamics model. The calcu...The dissipation phenomenon in the heavy-ion reaction at incident energy near the Fermi energy is studied by simulating the reaction ^129Xe＋^129Sn with the isospin-dependent quantum molecular dynamics model. The calculations involving a proper prescription of implementing the Pauli exclusion principle show that the isotropy ratio measured by free protons emitted in the reaction at energy slightly higher than the Fermi energy is in agreement with the experimental data recently released by the INDRA collaboration. A feasible value of the Pauli-blocking factor is estimated by comparing the theoretical results with the experimental data for the energy range considered here.展开更多
Analytical formulas for evaluating the relation of carrier density and Fermi energy for semiconductors with a tight-binding band have been proposed. The series expansions for a carrier density with fast convergency ha...Analytical formulas for evaluating the relation of carrier density and Fermi energy for semiconductors with a tight-binding band have been proposed. The series expansions for a carrier density with fast convergency have been obtained by means of a Bessel function. A simple and analytical formula for Fermi energy has been derived with the help of the Gauss integration method. The results of the proposed formulas are in good agreement with accurate numerical solutions. The formulas have been successfully used in the calculation of carrier density and Fermi energy in a miniband superlattice system. Their accuracy is in the order of 10-5.展开更多
Energy fluctuation of ideal Fermi gas trapped under generic power law potential U=Σ_(i=1)~d c_i|x_i/a_i|^(n_i) has been calculated in arbitrary dimensions.Energy fluctuation is scrutinized further in the degenerate l...Energy fluctuation of ideal Fermi gas trapped under generic power law potential U=Σ_(i=1)~d c_i|x_i/a_i|^(n_i) has been calculated in arbitrary dimensions.Energy fluctuation is scrutinized further in the degenerate limit μ>>K_B T with the help of Sommerfeld expansion.The dependence of energy fluctuation on dimensionality and power law potential is studied in detail.Most importantly our general result can not only exactly reproduce the recently published result regarding free and harmonically trapped ideal Fermi gas in d =3 but also can describe the outcome for any power law potential in arbitrary dimension.展开更多
The physical fundamentals and influences upon electrode materials＇ open-circuit voltage （OCV） and the spatial distribution of electrochemical potential in the full cell are briefly reviewed. We hope to illustrate t...The physical fundamentals and influences upon electrode materials＇ open-circuit voltage （OCV） and the spatial distribution of electrochemical potential in the full cell are briefly reviewed. We hope to illustrate that a better understanding of these scientific problems can help to develop and design high voltage cathodes and interfaces with low Ohmic drop. OCV is one of the main indices to evaluate the performance of lithium ion batteries （LIBs）, and the enhancement of OCV shows promise as a way to increase the energy density. Besides, the severe potential drop at the interfaces indicates high resistance there, which is one of the key factors limiting power density.展开更多
The electronic structures of (CdSe)n/(ZnSe)m strained-lager soperfattice (SLS) were investigated by the recursion method in the tight-bindiop opproximation. The total,local, and partial density of states were calculat...The electronic structures of (CdSe)n/(ZnSe)m strained-lager soperfattice (SLS) were investigated by the recursion method in the tight-bindiop opproximation. The total,local, and partial density of states were calculated for n=1, m=5.The total density of states (TDOS) for bulk CdSe, ZnSe and n=1, 3, m=1, 3, 5, for SLS were investigated.Fermi energy, the band gap, the valence of an atom, and the ionization potential and the electron affinity were discassed.展开更多
Co thin films were subjected to 50 keV carbon ion implantation.At the dose of 2.5× 10^(17)/cm^2,a hexagonal Co-carbide phase was observed for the first time.The lattice con- stants from electron diffraction are a...Co thin films were subjected to 50 keV carbon ion implantation.At the dose of 2.5× 10^(17)/cm^2,a hexagonal Co-carbide phase was observed for the first time.The lattice con- stants from electron diffraction are a=0.2685 nm and c=0.4335 nm.The phase does not dis- appear until the dose of 9×10^(17)/cm^2.Auger spectra showed that the stoichiometry was Co_(2-3)C.The behavior of the ferromagnetic carbides along the descending sequence of Ni-Fe-Co by Fermi energy of solids was interpreted.Furthermore,based on the kinetic con- dition of phase transformation and the band theory of solids,a possible explanation about the difference of the results of ion-metallurgy and thermal metallurgy was proposed.展开更多
Ashcroft＇s local empty core （EMC） model pseudopotential in the second-order perturbation theory is used to study the electron dispersion relation, the Fermi energy, and deviation in the Fermi energy from free elect...Ashcroft＇s local empty core （EMC） model pseudopotential in the second-order perturbation theory is used to study the electron dispersion relation, the Fermi energy, and deviation in the Fermi energy from free electron value for the liquid alkali metals and their equiatomic binary alloys for the first time. In the present computation, the use of pseudo-alloy-atom model （PAA） is proposed and found successful. The influence of the six different forms of the local field correction functions proposed by Hartree （H）, Vashishta Singwi （VS）, Taylor （T）, lehimaru-Utsumi （IU）, Farid et al. （F）, and Sarkar et al. （S） on the aforesaid electronic properties is examined explicitly, which reflects the varying effects of screening. The depth of the negative hump in the electron dispersion of liquid alkalis decreases in the order Li --→ K, except for Rb and Cs, it increases. The results of alloys are in predictive nature.展开更多
Some thermodynamic parnmeters of Pd-In alloys with 2 to 70 at. H indium have been determined in the temperuture range 800 to 1000℃ from e.m.f measurements ongalvanic cells with an onsen-cotzducting solid electrolyte....Some thermodynamic parnmeters of Pd-In alloys with 2 to 70 at. H indium have been determined in the temperuture range 800 to 1000℃ from e.m.f measurements ongalvanic cells with an onsen-cotzducting solid electrolyte. Heats of tnising calculated hem the activities are in excellent agreement with calorimetric data. The relative partial excess hee enengy of indiurn assumes unnsually larpe negative values ap to-174kJ/mol for Pd-rich alloys. Two efficts are discussed to account for the non-idealproperties: The rise Of Fermi enerpy as the valence electron8 of indium enter the 4dand 5sP bands of the alloy and the lattice distortion brought about by the differentmolar volumes of the cofnponents. The rise of the Fermi enerpy, as determlned fromthe activity data, indicates a strict adherence of the alloys to the rigid band model.展开更多
The equilibrium p-c-T data were determined by a microbalance in a vacuum system at hydrogen pressures up to 3.5 MPa on four Pd-In alloys between 3.64 and 14.53 at. % In as well as on Pure Pd. The results are similar t...The equilibrium p-c-T data were determined by a microbalance in a vacuum system at hydrogen pressures up to 3.5 MPa on four Pd-In alloys between 3.64 and 14.53 at. % In as well as on Pure Pd. The results are similar to those obtained on the analogous alloys Pd-Ag and Pd-Sn and are interpreted in the same manner. In has two opposing effects upon the solubility of H in the Pd alloys, i.e., increase of the Fermi energy upon the donation of valence electrons and a lattice dilatation. At valence electron concentrations below 0.5, the lattice dilatation predominates and the H solubility is increased with addition of In. At valence electron concentrations above 0.5, the influence of the elevated Fermi energy predominates and the H solubility is lowered by addition of In. The molar enthalpy of Pd hydriding at infinite dilution is strongly increased with increasing In content, but the molar entropy is not nearly as much affected by the Presence of In. The excess chemical potential of hydrogen at small hydrogen concentrations and at a given temperature increases with an increase of In content. The apparent H-H attractive interaction energy, W H-H, is decreased by the presence of In. The trend is also similar to that found for the Pd-Ag-H and Pd-Sn-H system.展开更多
TheMigdal–Eliashberg(ME)formalism provides a reliable framework for describing phonon-mediated superconductivity in the adiabatic regime,where the Fermi energy exceeds the characteristic phonon energy.Here,we extend ...TheMigdal–Eliashberg(ME)formalism provides a reliable framework for describing phonon-mediated superconductivity in the adiabatic regime,where the Fermi energy exceeds the characteristic phonon energy.Here,we extend this framework by incorporating first-order vertex corrections to the electron–phonon(e–ph)interaction and evaluating their impact on H_(3)S and Pb using first-principles calculations.For H_(3)S,where the adiabatic assumption breaks down,vertex corrections to the e–ph coupling are substantial.Combined with phonon anharmonicity and the energy dependence of the electronic density of states,these effects yield a predicted critical temperature T_(c)in excellent agreement with experiment.In contrast,for elemental Pb,where the adiabatic limit holds,vertex corrections are negligible,and the calculated T_(c)and gap closely match standard ME predictions.This study demonstrates the importance of non-adiabatic corrections in strongly coupled high-T_(c)hydrides and establishes a robust first-principles framework for accurately predicting superconducting properties across different regimes.展开更多
基金Supported by the National Natural Science Foundation Of China under Grant Nos 11265013,11175074,11264033 and 11464040
文摘The dissipation phenomenon in the heavy-ion reaction at incident energy near the Fermi energy is studied by simulating the reaction ^129Xe＋^129Sn with the isospin-dependent quantum molecular dynamics model. The calculations involving a proper prescription of implementing the Pauli exclusion principle show that the isotropy ratio measured by free protons emitted in the reaction at energy slightly higher than the Fermi energy is in agreement with the experimental data recently released by the INDRA collaboration. A feasible value of the Pauli-blocking factor is estimated by comparing the theoretical results with the experimental data for the energy range considered here.
文摘Analytical formulas for evaluating the relation of carrier density and Fermi energy for semiconductors with a tight-binding band have been proposed. The series expansions for a carrier density with fast convergency have been obtained by means of a Bessel function. A simple and analytical formula for Fermi energy has been derived with the help of the Gauss integration method. The results of the proposed formulas are in good agreement with accurate numerical solutions. The formulas have been successfully used in the calculation of carrier density and Fermi energy in a miniband superlattice system. Their accuracy is in the order of 10-5.
文摘Energy fluctuation of ideal Fermi gas trapped under generic power law potential U=Σ_(i=1)~d c_i|x_i/a_i|^(n_i) has been calculated in arbitrary dimensions.Energy fluctuation is scrutinized further in the degenerate limit μ>>K_B T with the help of Sommerfeld expansion.The dependence of energy fluctuation on dimensionality and power law potential is studied in detail.Most importantly our general result can not only exactly reproduce the recently published result regarding free and harmonically trapped ideal Fermi gas in d =3 but also can describe the outcome for any power law potential in arbitrary dimension.
基金supported by the National Natural Science Foundation of China(Grant Nos.51325206 and 51372228)National Basic Research Program of China(Grant No.2012CB932900)Shanghai Pujiang Program,China(Grant No.14PJ1403900)
文摘The physical fundamentals and influences upon electrode materials＇ open-circuit voltage （OCV） and the spatial distribution of electrochemical potential in the full cell are briefly reviewed. We hope to illustrate that a better understanding of these scientific problems can help to develop and design high voltage cathodes and interfaces with low Ohmic drop. OCV is one of the main indices to evaluate the performance of lithium ion batteries （LIBs）, and the enhancement of OCV shows promise as a way to increase the energy density. Besides, the severe potential drop at the interfaces indicates high resistance there, which is one of the key factors limiting power density.
文摘The electronic structures of (CdSe)n/(ZnSe)m strained-lager soperfattice (SLS) were investigated by the recursion method in the tight-bindiop opproximation. The total,local, and partial density of states were calculated for n=1, m=5.The total density of states (TDOS) for bulk CdSe, ZnSe and n=1, 3, m=1, 3, 5, for SLS were investigated.Fermi energy, the band gap, the valence of an atom, and the ionization potential and the electron affinity were discassed.
文摘Co thin films were subjected to 50 keV carbon ion implantation.At the dose of 2.5× 10^(17)/cm^2,a hexagonal Co-carbide phase was observed for the first time.The lattice con- stants from electron diffraction are a=0.2685 nm and c=0.4335 nm.The phase does not dis- appear until the dose of 9×10^(17)/cm^2.Auger spectra showed that the stoichiometry was Co_(2-3)C.The behavior of the ferromagnetic carbides along the descending sequence of Ni-Fe-Co by Fermi energy of solids was interpreted.Furthermore,based on the kinetic con- dition of phase transformation and the band theory of solids,a possible explanation about the difference of the results of ion-metallurgy and thermal metallurgy was proposed.
文摘Ashcroft＇s local empty core （EMC） model pseudopotential in the second-order perturbation theory is used to study the electron dispersion relation, the Fermi energy, and deviation in the Fermi energy from free electron value for the liquid alkali metals and their equiatomic binary alloys for the first time. In the present computation, the use of pseudo-alloy-atom model （PAA） is proposed and found successful. The influence of the six different forms of the local field correction functions proposed by Hartree （H）, Vashishta Singwi （VS）, Taylor （T）, lehimaru-Utsumi （IU）, Farid et al. （F）, and Sarkar et al. （S） on the aforesaid electronic properties is examined explicitly, which reflects the varying effects of screening. The depth of the negative hump in the electron dispersion of liquid alkalis decreases in the order Li --→ K, except for Rb and Cs, it increases. The results of alloys are in predictive nature.
文摘Some thermodynamic parnmeters of Pd-In alloys with 2 to 70 at. H indium have been determined in the temperuture range 800 to 1000℃ from e.m.f measurements ongalvanic cells with an onsen-cotzducting solid electrolyte. Heats of tnising calculated hem the activities are in excellent agreement with calorimetric data. The relative partial excess hee enengy of indiurn assumes unnsually larpe negative values ap to-174kJ/mol for Pd-rich alloys. Two efficts are discussed to account for the non-idealproperties: The rise Of Fermi enerpy as the valence electron8 of indium enter the 4dand 5sP bands of the alloy and the lattice distortion brought about by the differentmolar volumes of the cofnponents. The rise of the Fermi enerpy, as determlned fromthe activity data, indicates a strict adherence of the alloys to the rigid band model.
文摘The equilibrium p-c-T data were determined by a microbalance in a vacuum system at hydrogen pressures up to 3.5 MPa on four Pd-In alloys between 3.64 and 14.53 at. % In as well as on Pure Pd. The results are similar to those obtained on the analogous alloys Pd-Ag and Pd-Sn and are interpreted in the same manner. In has two opposing effects upon the solubility of H in the Pd alloys, i.e., increase of the Fermi energy upon the donation of valence electrons and a lattice dilatation. At valence electron concentrations below 0.5, the lattice dilatation predominates and the H solubility is increased with addition of In. At valence electron concentrations above 0.5, the influence of the elevated Fermi energy predominates and the H solubility is lowered by addition of In. The molar enthalpy of Pd hydriding at infinite dilution is strongly increased with increasing In content, but the molar entropy is not nearly as much affected by the Presence of In. The excess chemical potential of hydrogen at small hydrogen concentrations and at a given temperature increases with an increase of In content. The apparent H-H attractive interaction energy, W H-H, is decreased by the presence of In. The trend is also similar to that found for the Pd-Ag-H and Pd-Sn-H system.
基金supported by the National Science Foundation(NSF)under Award No.DMR-2035518Part of this research was supported by the NSF,Office of Advanced Cyberinfrastructure under Grant No.2103991 of the Cyberinfrastructure for Sustained Scientific(parallelization of the isotropic superconductivity module)Computational resources were provided by the Frontera and Stampede3 supercomputers at the Texas Advanced Computing Center(TACC)at The University of Texas at Austin(http://www.tacc.utexas.edu),supported through the Leadership Resource Allocation(LRAC)award DMR22004 and the ACCESS allocation TG-DMR180071,respectively.
文摘TheMigdal–Eliashberg(ME)formalism provides a reliable framework for describing phonon-mediated superconductivity in the adiabatic regime,where the Fermi energy exceeds the characteristic phonon energy.Here,we extend this framework by incorporating first-order vertex corrections to the electron–phonon(e–ph)interaction and evaluating their impact on H_(3)S and Pb using first-principles calculations.For H_(3)S,where the adiabatic assumption breaks down,vertex corrections to the e–ph coupling are substantial.Combined with phonon anharmonicity and the energy dependence of the electronic density of states,these effects yield a predicted critical temperature T_(c)in excellent agreement with experiment.In contrast,for elemental Pb,where the adiabatic limit holds,vertex corrections are negligible,and the calculated T_(c)and gap closely match standard ME predictions.This study demonstrates the importance of non-adiabatic corrections in strongly coupled high-T_(c)hydrides and establishes a robust first-principles framework for accurately predicting superconducting properties across different regimes.
