This work is devoted to the experimental determination of the electrostatic properties of the molecular 4-methyl-7-（salicylidene amino） coumarin（C17H13NC3） using high resolution x-ray diffraction data. The experim...This work is devoted to the experimental determination of the electrostatic properties of the molecular 4-methyl-7-（salicylidene amino） coumarin（C17H13NC3） using high resolution x-ray diffraction data. The experimental results are compared with those obtained theoretically from calculation type ab initio. The experimental investigation is carried out using the molecular electron charge density distribution based on the multipolar model of Hansen and Coppens. However the theoretical calculations are conducted by using the molecular orbital B3 LYP method and the Hartree-Fock（HF） approximation with the basis set 6-31G（d,p） implemented in the Gaussian program. In addition to the structural analysis,the thermal agitation is also analyzed in terms of rigid blocks to ensure a better precision of the results. Subsequently, the electrostatic atomic and molecular properties such as the net charges, the molecular dipolar moment to highlight the nature of charge transfer existing within the molecule studied are derived. Moreover, the obtained electrostatic potential enables the localization of the electropositive and the electronegative parts of the investigated molecule. The present work reports in detail the obtained electrostatic properties of this biologically important molecule.展开更多
Heavy-fermion superconductors (HFSCs) are regarded as outside the purview of BCS theory because it is usually constrained by the inequality , where EF, μ, kB, and θD are, respectively, the Fermi energy, chemical pot...Heavy-fermion superconductors (HFSCs) are regarded as outside the purview of BCS theory because it is usually constrained by the inequality , where EF, μ, kB, and θD are, respectively, the Fermi energy, chemical potential, Boltzmann constant, and the Debye temperature. We show that this restriction can be removed by incorporating μ into the equations for Tc and the gap Δ0 at T = 0. Further, when μ kBθD, we curtail the limits of the equations for Tc and Δ0 to avoid complex-valued solutions. The resulting equations are applied to a prominent member of the HFSC family, i.e., CeCoIn5, by appealing to ideas due to Born and Karmann, Suhl et al., and Bianconi et al. Since the equations now contain an additional variable μ, we find that 1) the Tc of the SC can be accounted for by a multitude of values of the (μ, λ) pair, λ being the interaction parameter;2) the λ vs. μ plot has a dome-like structure when μ kBθD;3) the (μ, λ) values obtained in 2) lead to reasonable results for the range of each of the following variables: Δ0, s, and n, where s is the ratio of the mass of a conduction electron and the free electron mass and n is the number density of charge carriers in the SC.展开更多
We address the Tc (s) and multiple gaps of La2CuO4 (LCO) via generalized BCS equations incorporating chemical potential. Appealing to the structure of the unit cell of LCO, which comprises sub- lattices with LaO and O...We address the Tc (s) and multiple gaps of La2CuO4 (LCO) via generalized BCS equations incorporating chemical potential. Appealing to the structure of the unit cell of LCO, which comprises sub- lattices with LaO and OLa layers and brings into play two Debye temperatures, the concept of itinerancy of electrons, and an insight provided by Tacon et al.’s recent experimental work concerned with YBa2Cu3O6.6 which reveals that very large electron-phonon coupling can occur in a very narrow region of phonon wavelengths, we are enabled to account for all values of its gap-to-Tc ratio (2Δ0/kBTc), i.e., 4.3, 7.1, ≈8 and 9.3, which were reported by Bednorz and Müller in their Nobel lecture. Our study predicts carrier concentrations corresponding to these gap values to lie in the range 1.3 × 1021 - 5.6 × 1021 cm-3, and values of 0.27 - 0.29 and 1.12 for the gap-to-Tc ratios of the smaller gaps.展开更多
This research paper provides valuable insight into the electronic,mechanical and transport properties of the Sr_(2)RuO_(2)F_(2)compound.The study shows that the Sr_(2)RuO_(4)compound exhibits a metallic ground state a...This research paper provides valuable insight into the electronic,mechanical and transport properties of the Sr_(2)RuO_(2)F_(2)compound.The study shows that the Sr_(2)RuO_(4)compound exhibits a metallic ground state and that the energy gap widens with oxygen substitution with fluorine.The concept of absolute deformation potential and its correlation with band energies and strains is explained using deformation potential theory.The paper also examines the mechanical features of Sr_(2)RuO_(2)F_(2)using the Voigt-Reuss-Hill approximation method and analyzes its elastic constants,bulk modulus and shear modulus,indicating flexibility and suitability for optoelectronic applications.The role of acoustic phonons in scattering rates and carrier mobility in Sr_(2)RuO_(2)F_(2)and its potential for phonon-mediated superconductivity is investigated.The intrinsic resistivity of electrons and holes under strain and its potential impact on superconductivity and electrical resistivity are also discussed.The insight provided by this study contributes to the current understanding of Sr_(2)RuO_(2)F_(2),and its potential applications.展开更多
In this research, the hydrogen bonds Y···H-X （X = C, N; Y = N, O） of thymine and uracil have been theoretically studied. The results show that hydrogen bond leads to bond length elongation and stretch...In this research, the hydrogen bonds Y···H-X （X = C, N; Y = N, O） of thymine and uracil have been theoretically studied. The results show that hydrogen bond leads to bond length elongation and stretches the frequency red-shift of N-H···Y. Meanwhile, the C-H···O bonds shorten and stretch the frequency blue-shift. They all belong to traditional hydrogen bonds. The intermolecular charge transfer caused by the intermolecular hyperconjugation s＊（N–H） → n（Y） and intramolecular charge redistribution by intramolecular hyperconjugation σ（C-H） →σ＊（C-N） play important roles in the formation of hydrogen bonds. According to thejudgment standards proposed by Bader and Popelier, these hydrogen bonds have typical electron density topological properties. Electrostatic surface potential （ESP） is a useful physicochemical property of a molecule that provides insights into inter- and intramolecular associations, as well as the prediction of likely sites of electrophilic and nucleophilic metabolic attack.展开更多
The current through a metal-semiconductor junction is mainly due to the majority carriers. Three distinctly different mechanisms exist in a Schottky diode： diffusion of the semiconductor carriers in metal, thermionic...The current through a metal-semiconductor junction is mainly due to the majority carriers. Three distinctly different mechanisms exist in a Schottky diode： diffusion of the semiconductor carriers in metal, thermionic emission-diffusion （TED） of carriers through a Schottky gate, and a mechanical quantum that pierces a tunnel through the gate. The system was solved by using a coupled Poisson-Boltzmann algorithm. Schottky BH is defined as the difference in energy between the Fermi level and the metal band carrier majority of the metal--semiconductor junction to the semiconductor contacts. The insulating layer converts the MS device in an MIS device and has a strong influence on its current-voltage （I-V） and the parameters ofa Schottky barrier from 3.7 to 15 eV. There are several possible reasons for the error that causes a deviation of the ideal behaviour of Schottky diodes with and without an interracial insulator layer. These include the particular distribution of interface states, the series resis- tance, bias voltage and temperature. The GaAs and its large concentration values of trap centers will participate in an increase in the process ofthermionic electrons and holes, which will in turn act on the I-V characteristic of the diode, and an overflow maximum value [NT = 3 × 10^20] is obtained. The I-V characteristics of Schottky diodes are in the hypothesis of a parabolic summit.展开更多
Density functional theory(DFT) calculations on three fullerene isomers of C72 were carried out at the B3LYP/6-31G* level.The optimized configurations and the electrostatic potential distributions have been obtained.Th...Density functional theory(DFT) calculations on three fullerene isomers of C72 were carried out at the B3LYP/6-31G* level.The optimized configurations and the electrostatic potential distributions have been obtained.The calculated results show that the C72(D6d) which satisfies the isolated-pentagon rule is the most stable structure among the three isomers of C72,while the potential minimum Vmin(r) inside the sphere of C72(#10611) is the biggest one among the three isomers of C72 considered.So C72(#10611) is easier to accept electrons from the scandium atoms than the other two isomers.Upon endohedral doping by Sc2,the(#10611) isomer is more highly stabilized thermodynamically and kinetically.展开更多
文摘This work is devoted to the experimental determination of the electrostatic properties of the molecular 4-methyl-7-（salicylidene amino） coumarin（C17H13NC3） using high resolution x-ray diffraction data. The experimental results are compared with those obtained theoretically from calculation type ab initio. The experimental investigation is carried out using the molecular electron charge density distribution based on the multipolar model of Hansen and Coppens. However the theoretical calculations are conducted by using the molecular orbital B3 LYP method and the Hartree-Fock（HF） approximation with the basis set 6-31G（d,p） implemented in the Gaussian program. In addition to the structural analysis,the thermal agitation is also analyzed in terms of rigid blocks to ensure a better precision of the results. Subsequently, the electrostatic atomic and molecular properties such as the net charges, the molecular dipolar moment to highlight the nature of charge transfer existing within the molecule studied are derived. Moreover, the obtained electrostatic potential enables the localization of the electropositive and the electronegative parts of the investigated molecule. The present work reports in detail the obtained electrostatic properties of this biologically important molecule.
文摘Heavy-fermion superconductors (HFSCs) are regarded as outside the purview of BCS theory because it is usually constrained by the inequality , where EF, μ, kB, and θD are, respectively, the Fermi energy, chemical potential, Boltzmann constant, and the Debye temperature. We show that this restriction can be removed by incorporating μ into the equations for Tc and the gap Δ0 at T = 0. Further, when μ kBθD, we curtail the limits of the equations for Tc and Δ0 to avoid complex-valued solutions. The resulting equations are applied to a prominent member of the HFSC family, i.e., CeCoIn5, by appealing to ideas due to Born and Karmann, Suhl et al., and Bianconi et al. Since the equations now contain an additional variable μ, we find that 1) the Tc of the SC can be accounted for by a multitude of values of the (μ, λ) pair, λ being the interaction parameter;2) the λ vs. μ plot has a dome-like structure when μ kBθD;3) the (μ, λ) values obtained in 2) lead to reasonable results for the range of each of the following variables: Δ0, s, and n, where s is the ratio of the mass of a conduction electron and the free electron mass and n is the number density of charge carriers in the SC.
文摘We address the Tc (s) and multiple gaps of La2CuO4 (LCO) via generalized BCS equations incorporating chemical potential. Appealing to the structure of the unit cell of LCO, which comprises sub- lattices with LaO and OLa layers and brings into play two Debye temperatures, the concept of itinerancy of electrons, and an insight provided by Tacon et al.’s recent experimental work concerned with YBa2Cu3O6.6 which reveals that very large electron-phonon coupling can occur in a very narrow region of phonon wavelengths, we are enabled to account for all values of its gap-to-Tc ratio (2Δ0/kBTc), i.e., 4.3, 7.1, ≈8 and 9.3, which were reported by Bednorz and Müller in their Nobel lecture. Our study predicts carrier concentrations corresponding to these gap values to lie in the range 1.3 × 1021 - 5.6 × 1021 cm-3, and values of 0.27 - 0.29 and 1.12 for the gap-to-Tc ratios of the smaller gaps.
文摘This research paper provides valuable insight into the electronic,mechanical and transport properties of the Sr_(2)RuO_(2)F_(2)compound.The study shows that the Sr_(2)RuO_(4)compound exhibits a metallic ground state and that the energy gap widens with oxygen substitution with fluorine.The concept of absolute deformation potential and its correlation with band energies and strains is explained using deformation potential theory.The paper also examines the mechanical features of Sr_(2)RuO_(2)F_(2)using the Voigt-Reuss-Hill approximation method and analyzes its elastic constants,bulk modulus and shear modulus,indicating flexibility and suitability for optoelectronic applications.The role of acoustic phonons in scattering rates and carrier mobility in Sr_(2)RuO_(2)F_(2)and its potential for phonon-mediated superconductivity is investigated.The intrinsic resistivity of electrons and holes under strain and its potential impact on superconductivity and electrical resistivity are also discussed.The insight provided by this study contributes to the current understanding of Sr_(2)RuO_(2)F_(2),and its potential applications.
基金Supported by the National Natural Science Foundation of China(20873103)
文摘In this research, the hydrogen bonds Y···H-X （X = C, N; Y = N, O） of thymine and uracil have been theoretically studied. The results show that hydrogen bond leads to bond length elongation and stretches the frequency red-shift of N-H···Y. Meanwhile, the C-H···O bonds shorten and stretch the frequency blue-shift. They all belong to traditional hydrogen bonds. The intermolecular charge transfer caused by the intermolecular hyperconjugation s＊（N–H） → n（Y） and intramolecular charge redistribution by intramolecular hyperconjugation σ（C-H） →σ＊（C-N） play important roles in the formation of hydrogen bonds. According to thejudgment standards proposed by Bader and Popelier, these hydrogen bonds have typical electron density topological properties. Electrostatic surface potential （ESP） is a useful physicochemical property of a molecule that provides insights into inter- and intramolecular associations, as well as the prediction of likely sites of electrophilic and nucleophilic metabolic attack.
基金HUANG Ying was supported by the Natural Science Foundation of Hunan Province,China (11JJ5065)Hunan College Student Research Study,Innovative Experiments,China (Xiang Jiao Tong [2011] 272)+4 种基金"Twelfth Five-Year" Key Discipline of Hunan University of Chinese Medicine-Pharmaceutical Analysis Science,ChinaZHANG Peng-Fei was supported by the Funds from the Major New Drug Discovery Science and Technology,China (2012ZX09303013-06)National Natural Science Foundation of China (81272609)Public Health Department of Hunan Scientific Research Foundation,China (B2010-004)LIU Liang-Hong was supported by the 2012 Innovation Program of Hunan University of Chinese Medicine for Postgraduate Students,China (2012cx07)~~
文摘The current through a metal-semiconductor junction is mainly due to the majority carriers. Three distinctly different mechanisms exist in a Schottky diode： diffusion of the semiconductor carriers in metal, thermionic emission-diffusion （TED） of carriers through a Schottky gate, and a mechanical quantum that pierces a tunnel through the gate. The system was solved by using a coupled Poisson-Boltzmann algorithm. Schottky BH is defined as the difference in energy between the Fermi level and the metal band carrier majority of the metal--semiconductor junction to the semiconductor contacts. The insulating layer converts the MS device in an MIS device and has a strong influence on its current-voltage （I-V） and the parameters ofa Schottky barrier from 3.7 to 15 eV. There are several possible reasons for the error that causes a deviation of the ideal behaviour of Schottky diodes with and without an interracial insulator layer. These include the particular distribution of interface states, the series resis- tance, bias voltage and temperature. The GaAs and its large concentration values of trap centers will participate in an increase in the process ofthermionic electrons and holes, which will in turn act on the I-V characteristic of the diode, and an overflow maximum value [NT = 3 × 10^20] is obtained. The I-V characteristics of Schottky diodes are in the hypothesis of a parabolic summit.
文摘Density functional theory(DFT) calculations on three fullerene isomers of C72 were carried out at the B3LYP/6-31G* level.The optimized configurations and the electrostatic potential distributions have been obtained.The calculated results show that the C72(D6d) which satisfies the isolated-pentagon rule is the most stable structure among the three isomers of C72,while the potential minimum Vmin(r) inside the sphere of C72(#10611) is the biggest one among the three isomers of C72 considered.So C72(#10611) is easier to accept electrons from the scandium atoms than the other two isomers.Upon endohedral doping by Sc2,the(#10611) isomer is more highly stabilized thermodynamically and kinetically.
