The chiral sulfide Y4InSbS9 has been prepared from stoichiometric elements at 1223 K in an evacuated silica tube. It crystallizes in the chiral tetragonal space group P43212 with a = 9.8784(3), c = 27.3106(16) A, ...The chiral sulfide Y4InSbS9 has been prepared from stoichiometric elements at 1223 K in an evacuated silica tube. It crystallizes in the chiral tetragonal space group P43212 with a = 9.8784(3), c = 27.3106(16) A, V = 2665.04(19) A^3, Z = 8, Mr = 880.75, Dc = 4.390 g/cm^3, μ = 22.285 mm^–1, F(000) = 3200, the final R = 0.0302 and wR = 0.0669 for 2961 observed reflections with I 〉 2σ(I). The structure features infinite helical chains of [In2Sb2S(11)^10–]∞ propagating along the c direction and they are separated by isolated Y^3+ cations and S2– anions. UV/Vis diffuse reflectance spectroscopy study shows that its optical gap is around 1.94 eV. Density functional theory(DFT) study indicates an indirect band gap with an electronic transfer excitation of S 3p to Y 5d orbital electrons.展开更多
Third-order nonlinear optical (NLO) materials have broad application prospects in high-density data storage, optical computer, modern laser technology, and other high-tech industries. The structures and frequencies of...Third-order nonlinear optical (NLO) materials have broad application prospects in high-density data storage, optical computer, modern laser technology, and other high-tech industries. The structures and frequencies of Dinaphtho[2,3-b:2’,3’-d]thiophene-5,7,12,13-tetraone (DNTTRA) and its 36 derivatives containing azobenzene were calculated by using density functional theory B3LYP and M06-2X methods at 6-311++g(d, p) level, respectively. Besides, the atomic charges of natural bond orbitals (NBO) were analyzed. The frontier orbitals and electron absorption spectra of A-G5 molecule were calculated by TD-DFT (TD-B3LYP/6-311++g(d, p) and TD-M06-2X/6-311++g(d, p)). The NLO properties were calculated by effective finite field FF method and self-compiled program. The results show that 36 molecules of these six series are D-π-A-π-D structures. The third-order NLO coefficients γ (second-order hyperpolarizability) of the D series molecules are the largest among the six series, reaching 10<sup>7</sup> atomic units (10<sup><span style="color:#4F4F4F;font-family:-apple-system, " font-size:14px;white-space:normal;background-color:#ffffff;"="">-</span>33</sup> esu) of order of magnitude, showing good third-order NLO properties. Last, the third-order NLO properties of the azobenzene ring can be improved by introducing strong electron donor groups (e.g. -N(CH<sub>3</sub>)<sub>2</sub> or -NHCH<sub>3</sub>) in the azobenzene ring, so that the third-order NLO materials with good performance can be obtained.展开更多
A triphenylamine-containing Schiff base ligand(L), namely, N-(4-(1 H-imidazol-1-yl)benzylidene)-N,N-diphenylbenzene-1,4-diamine, was synthesized and characterized. By coordination of the ligand with CdI2, a complex Cd...A triphenylamine-containing Schiff base ligand(L), namely, N-(4-(1 H-imidazol-1-yl)benzylidene)-N,N-diphenylbenzene-1,4-diamine, was synthesized and characterized. By coordination of the ligand with CdI2, a complex CdI2 L2 was obtained. The structure of the complex was analyzed through single-crystal X-ray diffraction. It crystallizes in monoclinic, space group P21/c with a = 25.277(5), b = 11.176(5), c = 17.912(5)A,β= 106.056(5)°, V = 4863(3)A3, Z = 4, Dc =1.633 Mg/m3, F(000)= 2360,Μr = 1195.19,μ= 1.766 mm-1, the final R = 0.0323 and wR = 0.0758 for 33414 observed reflections with I > 2?(I). The linear absorption spectra of the complex were experimentally and theoretically studied. And the third-order nonlinear optical(NLO) property of the complex was also measured through Z-scan technique.展开更多
The geometric structures, electronic properties, total and binding energies, harmonic frequencies, the highest occupied molecular orbital to the lowest unoccupied molecular orbital energy gaps, and the vertical ioniza...The geometric structures, electronic properties, total and binding energies, harmonic frequencies, the highest occupied molecular orbital to the lowest unoccupied molecular orbital energy gaps, and the vertical ionization potential energies of small LimBn (m+ n = 12) clusters were investigated by the density functional theory B3LYP with a 6-31 I+G (2d, 2p) basis set. All the calculations were performed using the Gaussian09 program. For the study of the LimBn clusters, the global minimum of the B 12 cluster was chosen as the starting point and the boron atoms were gradually replaced by Li atoms. The results showed that as the number of Li atoms increased, the stability of the LimBn cluster decreased and the physical and chemical properties became more active. In addition, on average there was a large charge transfer from the Li atoms to the B atoms.展开更多
Cyclo[18]carbon has received considerable attention thanks to its novel geometric configuration and special electronic structure.Superalkalis have low ionization energy.Doping a superalkali in cyclo[18]carbon is an ef...Cyclo[18]carbon has received considerable attention thanks to its novel geometric configuration and special electronic structure.Superalkalis have low ionization energy.Doping a superalkali in cyclo[18]carbon is an effective method to improve the optical properties of the system because considerable electron transfer occurs.In this paper,the geometry,bonding properties,electronic structure,absorption spectrum,and nonlinear optical(NLO)properties of superalkaline M_(3)O(M=Li,Na)-doped cyclo[18]carbon were studied by using density functional theory.M_(3)O and the C_(18) rings are not coplanar.The C_(18) ring still exhibits alternating long and short bonds.The charge transfer between M_(3)O and C_(18) forms stable[M_(3)O]+[C_(18)]-ionic complexes.C_(18)M_(3)O(M=Li,Na)shows striking optical nonlinearity,i.e.,their first-and second-order hyperpolarizability(βvec andγ||)increase considerably atλ=1907 nm and 1460 nm.展开更多
The electronic structures and optical properties of intrinsic SnO2, Zn-doped SnO2, SnO2 with Sn va- cancy (Vsn) and Zn-doped SnO2 with Sn vacancy are explored by using first-principles calculations. Zn-doped SnO2 is...The electronic structures and optical properties of intrinsic SnO2, Zn-doped SnO2, SnO2 with Sn va- cancy (Vsn) and Zn-doped SnO2 with Sn vacancy are explored by using first-principles calculations. Zn-doped SnO2 is a p-type semiconductor material, whose Fermi level shifts into the valence band when Zn atoms substitute Sn atoms, and the unoccupied states on the top of the valence band come from Zn 3d and O 2p states. Sn vacancies increase the relative hole number of Zn-doped SnO2, which results in a possible increase in the conductivity of Zn-doped SnO2. The Zn-doped SnO2 shows distinct visible light absorption, the increased absorption can be seen apparently with the presence of Sn vacancies in the crystal, and the blue-shift of optical spectra can be observed.展开更多
We present a system study on the electronic structure and optical property of boron doped semiconducting graphene nanoribbons using the density functional theory. Energy band structure, density of states, deformation ...We present a system study on the electronic structure and optical property of boron doped semiconducting graphene nanoribbons using the density functional theory. Energy band structure, density of states, deformation density, Mulliken popular and optical spectra are considered to show the special electronic structure of boron doped semiconducting graphene nanoribbons. The C-B bond form is discussed in detail. From our analysis it is concluded that the Fermi energy of boron doped semiconducting graphene nanoribbons gets lower than that of intrinsic semiconducting graphene nanoribbons. Our results also show that the boron doped semiconducting graphene nanoribbons behave as p-type semiconducting and that the absorption coefficient of boron doped armchair graphene nanoribbons is generally enhanced between 2.0 eV and 3.3 eV. Therefore, our results have a great significance in developing nano-material for fabricating the nano-photovoltaic devices.展开更多
Copper nitride (Cu3N) films were prepared by reactive radio frequency magnetron sputtering at various nitrogen partial pressures, and the films were annealed at different temperatures. The crystal structure of the f...Copper nitride (Cu3N) films were prepared by reactive radio frequency magnetron sputtering at various nitrogen partial pressures, and the films were annealed at different temperatures. The crystal structure of the films was identified by X-ray diffraction technique. The Cu3N films have a cubic anti-ReO3 structure, and lattice constant is 0.3855 nm. With increasing nitrogen partial pressure, the Cu3N films are strongly textured with the crystal direction [100]. The atomic force microscope images show that the films presence a smooth and compact morphology with nanocrystallites of about 70 nm in size. The films were further characterized by UV-visible spectrometer, and the optical band gap of the films was calculated from the Tauc equation. The typical value of optical band gap of the films is about 1.75 eV, and it increases with increasing nitrogen partial pressure. The thermal property of the films was measured by thermogravimetry, and the decomposition temperature of the films was about 530 K.展开更多
The first-principles calculations are performed to examine structural,mechanical,and electronic properties at large strain for a monolayer C_(4)N_(4),which has been predicted as an anchoring promising material to atte...The first-principles calculations are performed to examine structural,mechanical,and electronic properties at large strain for a monolayer C_(4)N_(4),which has been predicted as an anchoring promising material to attenuate shuttle effect in Li–S batteries stemming from its large absorption energy and low diffusion energy barrier.Our results show that the ideal strengths of C_(4)N_(4)under tension and pure shear deformation conditions reach 13.9 GPa and 12.5 GPa when the strains are 0.07 and 0.28,respectively.The folded five-membered rings and diverse bonding modes between carbon and nitrogen atoms enhance the ability to resist plastic deformation of C_(4)N_(4).The orderly bond-rearranging behaviors under the weak tensile loading path along the[100]direction cause the impressive semiconductor–metal transition and inverse semiconductor–metal transition.The present results enrich the knowledge of the structure and electronic properties of C_(4)N_(4)under deformations and shed light on exploring other two-dimensional materials under diverse loading conditions.展开更多
The structures,mechanical properties and electronic structures of M metals(M=Ti,V,Cr,Mn and Fe)dopedβ-Si_(3)N_(4) were investigated by First-principles calculations within CASTEP.The calculated lattice parameters of...The structures,mechanical properties and electronic structures of M metals(M=Ti,V,Cr,Mn and Fe)dopedβ-Si_(3)N_(4) were investigated by First-principles calculations within CASTEP.The calculated lattice parameters ofβ-Si_(3)N_(4) were consistent with previous date.The cohesive energy and formation enthalpy show that initialβ-Si_(3)N_(4) has the highest structural stability.The calculated elastic constant and the Voigt-Reuss-Hill approximation indicate that elastic moduli ofβ-Si_(3)N_(4) are slightly reduced by M doping.Based on Poisson’s and Pugh’s ratio,β-Si_(3)N_(4) is a ductile material and the toughness ofβ-Si_(3)N_(4) increases with M doping,and Fe doping exhibited the best toughness.The results of density of states,charge distributions and overlapping populations indicate thatβ-Si_(3)N_(4) has the strong covalent and ionic bond strength between N and Si.展开更多
Structural, electronic and optical properties of Sc-based aluminum-nitride alloy have been carried out with first-principles methods using both local density approximation (LDA) and Heyd-Scuseria-Ernzerhof (HSE) hybri...Structural, electronic and optical properties of Sc-based aluminum-nitride alloy have been carried out with first-principles methods using both local density approximation (LDA) and Heyd-Scuseria-Ernzerhof (HSE) hybrid functional. This latter provides a more accurate description of the lattice parameters, enthalpy of formation, electronic and optical properties of our alloy than standard DFT. We found the transition from wurtzite to rocksalt structures at 61% of Sc concentration. By increasing the scandium concentration, the lattice parameters and the band gap decrease. The HSE band gap is in good agreement with available experimental data. The existence of the strong hybridization between Sc 3d and N 2p indicates the transport of electrons from Sc to N atoms. Besides, it is shown that the insertion of the Sc atom leads to the redshift of the optical absorption edge. The optical absorption of Sc<sub>x</sub>Al<sub>1-x</sub>N is found to decrease with increasing Sc concentrations in the low energy range. Because of this, Sc<sub>x</sub>Al<sub>1-x</sub>N have a great potential for applications in photovoltaics and photocatalysis.展开更多
Rare earth luminescent materials have attracted significant attention due to their wide-ranging applications in the field of optoelectronics. This study aims to delve into the electronic structure and optical properti...Rare earth luminescent materials have attracted significant attention due to their wide-ranging applications in the field of optoelectronics. This study aims to delve into the electronic structure and optical properties of rare earth luminescent materials, with the goal of uncovering their importance in luminescence mechanisms and applications. Through theoretical calculations and experimental methods, we conducted in-depth analyses on materials composed of various rare earth elements. Regarding electronic structure, we utilized computational techniques such as density functional theory to investigate the band structure, valence state distribution, and electronic density of states of rare earth luminescent materials. The results indicate that the electronic structural differences among different rare earth elements notably influence their luminescence performance, providing crucial clues for explaining the luminescence mechanism. In terms of optical properties, we systematically examined the material’s optical behaviors through fluorescence spectroscopy, absorption spectroscopy, and other experimental approaches. We found that rare earth luminescent materials exhibit distinct absorption and emission characteristics at different wavelengths, closely related to the transition processes of their electronic energy levels. Furthermore, we studied the influence of varying doping concentrations and impurities on the material’s optical properties. Experimental outcomes reveal that appropriate doping can effectively regulate the emission intensity and wavelength, offering greater possibilities for material applications. In summary, this study comprehensively analyzed the electronic structure and optical properties of rare earth luminescent materials, providing deep insights into understanding their luminescence mechanisms and potential value in optoelectronic applications. In the future, these research findings will serve as crucial references for the technological advancement in fields such as LEDs, lasers, and bioimaging.展开更多
A system study of the three-dimensional normal stress for regulating electronic structure and magnetic property of Fe_2Ge is studied. The density states of Fe more than 92% contribution come from Fe 3d,the density sta...A system study of the three-dimensional normal stress for regulating electronic structure and magnetic property of Fe_2Ge is studied. The density states of Fe more than 92% contribution come from Fe 3d,the density states of Ge mainly contributed from Ge 4p and Ge 4s,and the Fe 3d spin induces the Ge 4p electron transfer. The inductive effect increases germanium electron energy,weakens the Fe spin density of states,opposes the stability of the ferromagnetic state. The magnetic moment varies from 5 to 3 μB with the stress charges from-30 to 30 GPa. The charge of Fe is negative whereas the Ge atom is positively charged,the Fe atom loses charge,the charge transfers to the Ge atom. The unevenly distributed charge forms the newoccupy state and spin polarization state in the Fe_2Ge electron structure system. The Fe is the electron donor,the total electron is transferred to Ge,but the total numbers of gain electron and total numbers of lost electron are not equal,so the Fe_2Ge electron system may have hybridization between the Fe 3d state and Ge 4p state.The magnetic of Fe_2Ge mainly comes from the unoccupied Fe 3d orbital,the Fe 3d is positive spinpolarization state and the spin-polarization strength is decreased,the Ge 4p is negative spin-polarization state and the spin-polarization strength are increased. M oreover,electrons-spin polarization is relevant to the structure parameters of the Fe_2Ge system,and controls spin-polarized electronic behavior by means of adjusting ferromagnetic.展开更多
Glycine is an active organic compound. It has been reported that it can be combined with H2SO4, HNO3, CaCl2 etc. to form single crystals. Recently, we have first found that NH2CH2COOH combined with H2C2O4 can form a n...Glycine is an active organic compound. It has been reported that it can be combined with H2SO4, HNO3, CaCl2 etc. to form single crystals. Recently, we have first found that NH2CH2COOH combined with H2C2O4 can form a new compound——glycine oxalate (the molecular formula is NH2CH4 COOH·H2C2O4). For simplicity, it is called GO. Growth and the properties of GO single crystal展开更多
Ⅰ. INTRODUCTION Not long ago, we found that NH2CH2COOH could combine with H2C2O4 to form NH2CH2COOH·H2C2O4 single crystal which may be simply written as GO. In NH2CH2COOH—H2C2O4—H2O system, another new crystal...Ⅰ. INTRODUCTION Not long ago, we found that NH2CH2COOH could combine with H2C2O4 to form NH2CH2COOH·H2C2O4 single crystal which may be simply written as GO. In NH2CH2COOH—H2C2O4—H2O system, another new crystal, diglycine展开更多
Using a new developed valence bond theory of intermetallic compound, the electronic structure and properties of TiAl were analysed systematically. It was determined that the valence electronic structure of Ti and Al a...Using a new developed valence bond theory of intermetallic compound, the electronic structure and properties of TiAl were analysed systematically. It was determined that the valence electronic structure of Ti and Al atom in TiAl to be [ (4sf)0.42 (4sc) 1.36 (3dc)2.22]Ti and[ (3sf)0.39 (3sc)0.59 (3dc)2.02 ] Al respectively. According to these electronic structure, lattice constant, cohesive energy, potential curve, bulk modulus and temperature dependence of linear thermal expansion coefficient have been calculated, most of the theoretical values of these properties are in good agreement with experiment ones.展开更多
The electronic structure and optical properties of CdGeAs2 were calculated by the first principle method using ultra-soft pseudo-potential approach of the plane wave based upon density functional theory (DFT). Mulli...The electronic structure and optical properties of CdGeAs2 were calculated by the first principle method using ultra-soft pseudo-potential approach of the plane wave based upon density functional theory (DFT). Mulliken population analysis showed that atomic orbital hybridization occurs when forming chemical bonds. The relationship between inter-band transition and optical properties was analyzed to provide a theoretical basis for investigating or controlling CdGeAs2 crystal defects.展开更多
The electronic structures and optical properties of II-III2-VI4 (II = Zn, Cd; III = In; VI = Se, Te) compounds are studied by the density functional theory (DFT) using the Vienna ab initio simulation package (VAS...The electronic structures and optical properties of II-III2-VI4 (II = Zn, Cd; III = In; VI = Se, Te) compounds are studied by the density functional theory (DFT) using the Vienna ab initio simulation package (VASP). Geometrical optimization of the unit cell is in good agreement with the experimental data. Our calculations show that the valence band maximum (VBM) and conduction band minimum (CBM) are located at G resulting in a direct energy gap. The optical properties are analyzed, and the independent second harmonic generation (SHG) coefficients are determined. By an analysis of the band structure, we can get that SHG response of the system can be attributed to the transitions from the bands near the top of valence band that are derived from the Se/Te p states to the unoccupied bands contributed by the p states of In atoms.展开更多
The systematic trends of electrionic structure and optical properties of rutile (P42/mnm) RuO2 have been cal- culated by using the plane-wave norm-conserving pseudopotential density functional theory (DFT) method ...The systematic trends of electrionic structure and optical properties of rutile (P42/mnm) RuO2 have been cal- culated by using the plane-wave norm-conserving pseudopotential density functional theory (DFT) method within the generalised gradient approximation (GGA) for the exchange-correlation potential. The obtained equilibrium structure parameters are in excellent agreement with the experimental data. The calculated bulk modulus and elastic constants are also in good agreement with the experimental data and available theoretical calculations. Analysis based on elec- tronic structure and pseudogap reveals that the bonding nature in RuO2 is a combination of covalent, ionic and metallic bonds. Based on a Kramers Kronig analysis of the reflectivity, we have obtained the spectral dependence of the real and imaginary parts of the complex dielectric constant (~1 and z2, respectively) and the refractive index (n); and comparisons have shown that the theoretical results agree well with the experimental data as well. Meanwhile, we have also calculated the absorption coefficient, reflectivity index, electron energy loss function of RuO2 for radiation up to 30 eV. As a result, the predicted reflectivity index is in good agreement with the experimental data at low energies.展开更多
The systematic trends and effect introduced by Zr and C co-doping to TiO2 of electronic structure and optical properties of anatase TiO2 have been calculated by the plane-wave ultra-soft pseudopotential density functi...The systematic trends and effect introduced by Zr and C co-doping to TiO2 of electronic structure and optical properties of anatase TiO2 have been calculated by the plane-wave ultra-soft pseudopotential density functional theory (DFT) method within the generalized gradient approximation (GGA) for the exchange-correlation potential. Through the current calculations, the density of states (DOS), energy band structure and optical absorption coefficients have been obtained for TiO2 and compared with the doped TiO2, and the influence of electronic structure and optical properties caused by Zr and C co-doping has been presented qualitatively together. The results revealed that the energy band gap has been decreased owing to the doped Zr and C, whereas the optical absorption coefficients have been increased in the region of 400~800 nm and a red shift of absorption band can be found. Accordingly, photo catalytic activity of TiO2 has been enhanced. The current calculations are in good agreement with the experimental data.展开更多
基金Supported by the National Natural Science Foundation of China(Nos.21201185 and 21661037)the Natural Science Foundation of Chongqing(Nos.cstc2013jcyjA50033 and cstc2015jcyjA0317)+2 种基金the Natural Science Foundation of Guizhou Province(Nos.JLKZS[2014]13 and[2014]42)the Project Foundation of Chongqing University of Education(No.16xjpt08)the Natural Science Foundation of State Key Laboratory of Structural Chemistry(No.20140004)
文摘The chiral sulfide Y4InSbS9 has been prepared from stoichiometric elements at 1223 K in an evacuated silica tube. It crystallizes in the chiral tetragonal space group P43212 with a = 9.8784(3), c = 27.3106(16) A, V = 2665.04(19) A^3, Z = 8, Mr = 880.75, Dc = 4.390 g/cm^3, μ = 22.285 mm^–1, F(000) = 3200, the final R = 0.0302 and wR = 0.0669 for 2961 observed reflections with I 〉 2σ(I). The structure features infinite helical chains of [In2Sb2S(11)^10–]∞ propagating along the c direction and they are separated by isolated Y^3+ cations and S2– anions. UV/Vis diffuse reflectance spectroscopy study shows that its optical gap is around 1.94 eV. Density functional theory(DFT) study indicates an indirect band gap with an electronic transfer excitation of S 3p to Y 5d orbital electrons.
文摘Third-order nonlinear optical (NLO) materials have broad application prospects in high-density data storage, optical computer, modern laser technology, and other high-tech industries. The structures and frequencies of Dinaphtho[2,3-b:2’,3’-d]thiophene-5,7,12,13-tetraone (DNTTRA) and its 36 derivatives containing azobenzene were calculated by using density functional theory B3LYP and M06-2X methods at 6-311++g(d, p) level, respectively. Besides, the atomic charges of natural bond orbitals (NBO) were analyzed. The frontier orbitals and electron absorption spectra of A-G5 molecule were calculated by TD-DFT (TD-B3LYP/6-311++g(d, p) and TD-M06-2X/6-311++g(d, p)). The NLO properties were calculated by effective finite field FF method and self-compiled program. The results show that 36 molecules of these six series are D-π-A-π-D structures. The third-order NLO coefficients γ (second-order hyperpolarizability) of the D series molecules are the largest among the six series, reaching 10<sup>7</sup> atomic units (10<sup><span style="color:#4F4F4F;font-family:-apple-system, " font-size:14px;white-space:normal;background-color:#ffffff;"="">-</span>33</sup> esu) of order of magnitude, showing good third-order NLO properties. Last, the third-order NLO properties of the azobenzene ring can be improved by introducing strong electron donor groups (e.g. -N(CH<sub>3</sub>)<sub>2</sub> or -NHCH<sub>3</sub>) in the azobenzene ring, so that the third-order NLO materials with good performance can be obtained.
基金supported by the Major Project of Natural Science Research in Universities of Anhui Province(KJ2018ZD037,KJ2018A0333)Key Project of Youth Talents in Universities of Anhui Province(gxyqZD2017067)+4 种基金National Natural Science Foundation of China(21401024)Natural Science Foundation of Anhui Province(1508085MB21)National Students Research Training Program(201710371099,201710371019)Research Innovation Team of Fuyang Normal University(kytd201710)Horizontal Cooperation Project of Fuyang Municipal Government and Fuyang Normal University(XDHX2016011,XDHX2016004)
文摘A triphenylamine-containing Schiff base ligand(L), namely, N-(4-(1 H-imidazol-1-yl)benzylidene)-N,N-diphenylbenzene-1,4-diamine, was synthesized and characterized. By coordination of the ligand with CdI2, a complex CdI2 L2 was obtained. The structure of the complex was analyzed through single-crystal X-ray diffraction. It crystallizes in monoclinic, space group P21/c with a = 25.277(5), b = 11.176(5), c = 17.912(5)A,β= 106.056(5)°, V = 4863(3)A3, Z = 4, Dc =1.633 Mg/m3, F(000)= 2360,Μr = 1195.19,μ= 1.766 mm-1, the final R = 0.0323 and wR = 0.0758 for 33414 observed reflections with I > 2?(I). The linear absorption spectra of the complex were experimentally and theoretically studied. And the third-order nonlinear optical(NLO) property of the complex was also measured through Z-scan technique.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11264020 and 11364023)the Science Foundation of Education Committee of Jiangxi Province,China(Grant Nos.GJJ12463,11530,and 11540)+1 种基金the Doctoral Startup Fund of Jingguangshang University,China(Grant No.JZB11003)the Key Subject of Atomic and Molecular Physics in Jiangxi Province,China(Grant No.2011-2015)
文摘The geometric structures, electronic properties, total and binding energies, harmonic frequencies, the highest occupied molecular orbital to the lowest unoccupied molecular orbital energy gaps, and the vertical ionization potential energies of small LimBn (m+ n = 12) clusters were investigated by the density functional theory B3LYP with a 6-31 I+G (2d, 2p) basis set. All the calculations were performed using the Gaussian09 program. For the study of the LimBn clusters, the global minimum of the B 12 cluster was chosen as the starting point and the boron atoms were gradually replaced by Li atoms. The results showed that as the number of Li atoms increased, the stability of the LimBn cluster decreased and the physical and chemical properties became more active. In addition, on average there was a large charge transfer from the Li atoms to the B atoms.
基金Project supported by the Natural Science Foundation of Anhui Province(Grant No.1908085MA12)the National Natural Science Foundation of China(Grant No.21703222)。
文摘Cyclo[18]carbon has received considerable attention thanks to its novel geometric configuration and special electronic structure.Superalkalis have low ionization energy.Doping a superalkali in cyclo[18]carbon is an effective method to improve the optical properties of the system because considerable electron transfer occurs.In this paper,the geometry,bonding properties,electronic structure,absorption spectrum,and nonlinear optical(NLO)properties of superalkaline M_(3)O(M=Li,Na)-doped cyclo[18]carbon were studied by using density functional theory.M_(3)O and the C_(18) rings are not coplanar.The C_(18) ring still exhibits alternating long and short bonds.The charge transfer between M_(3)O and C_(18) forms stable[M_(3)O]+[C_(18)]-ionic complexes.C_(18)M_(3)O(M=Li,Na)shows striking optical nonlinearity,i.e.,their first-and second-order hyperpolarizability(βvec andγ||)increase considerably atλ=1907 nm and 1460 nm.
基金supported by the National Natural Science Foundation of China(No.10974077)the Innovation Project of Shandong Graduate Education,China(No.SDYY13093)
文摘The electronic structures and optical properties of intrinsic SnO2, Zn-doped SnO2, SnO2 with Sn va- cancy (Vsn) and Zn-doped SnO2 with Sn vacancy are explored by using first-principles calculations. Zn-doped SnO2 is a p-type semiconductor material, whose Fermi level shifts into the valence band when Zn atoms substitute Sn atoms, and the unoccupied states on the top of the valence band come from Zn 3d and O 2p states. Sn vacancies increase the relative hole number of Zn-doped SnO2, which results in a possible increase in the conductivity of Zn-doped SnO2. The Zn-doped SnO2 shows distinct visible light absorption, the increased absorption can be seen apparently with the presence of Sn vacancies in the crystal, and the blue-shift of optical spectra can be observed.
基金supported by the Natural Science Foundation of Fujian Province of China (Grant No. A0220001)Science Research Project of Leshan Vocational & Technical College (Grant No. KY2011001)the Key Research Project in Science and Technology of Leshan (Grant No. 2011GZD050)
文摘We present a system study on the electronic structure and optical property of boron doped semiconducting graphene nanoribbons using the density functional theory. Energy band structure, density of states, deformation density, Mulliken popular and optical spectra are considered to show the special electronic structure of boron doped semiconducting graphene nanoribbons. The C-B bond form is discussed in detail. From our analysis it is concluded that the Fermi energy of boron doped semiconducting graphene nanoribbons gets lower than that of intrinsic semiconducting graphene nanoribbons. Our results also show that the boron doped semiconducting graphene nanoribbons behave as p-type semiconducting and that the absorption coefficient of boron doped armchair graphene nanoribbons is generally enhanced between 2.0 eV and 3.3 eV. Therefore, our results have a great significance in developing nano-material for fabricating the nano-photovoltaic devices.
基金supported by the National Natural Science Foundation of China (Garnt No. 11064003)the Guangxi Natural Science Foundation of China(2010GXNSFA013122)
文摘Copper nitride (Cu3N) films were prepared by reactive radio frequency magnetron sputtering at various nitrogen partial pressures, and the films were annealed at different temperatures. The crystal structure of the films was identified by X-ray diffraction technique. The Cu3N films have a cubic anti-ReO3 structure, and lattice constant is 0.3855 nm. With increasing nitrogen partial pressure, the Cu3N films are strongly textured with the crystal direction [100]. The atomic force microscope images show that the films presence a smooth and compact morphology with nanocrystallites of about 70 nm in size. The films were further characterized by UV-visible spectrometer, and the optical band gap of the films was calculated from the Tauc equation. The typical value of optical band gap of the films is about 1.75 eV, and it increases with increasing nitrogen partial pressure. The thermal property of the films was measured by thermogravimetry, and the decomposition temperature of the films was about 530 K.
基金Project support by the National Natural Science Foundation of China(Grant Nos.11704044 and 12074140)。
文摘The first-principles calculations are performed to examine structural,mechanical,and electronic properties at large strain for a monolayer C_(4)N_(4),which has been predicted as an anchoring promising material to attenuate shuttle effect in Li–S batteries stemming from its large absorption energy and low diffusion energy barrier.Our results show that the ideal strengths of C_(4)N_(4)under tension and pure shear deformation conditions reach 13.9 GPa and 12.5 GPa when the strains are 0.07 and 0.28,respectively.The folded five-membered rings and diverse bonding modes between carbon and nitrogen atoms enhance the ability to resist plastic deformation of C_(4)N_(4).The orderly bond-rearranging behaviors under the weak tensile loading path along the[100]direction cause the impressive semiconductor–metal transition and inverse semiconductor–metal transition.The present results enrich the knowledge of the structure and electronic properties of C_(4)N_(4)under deformations and shed light on exploring other two-dimensional materials under diverse loading conditions.
文摘The structures,mechanical properties and electronic structures of M metals(M=Ti,V,Cr,Mn and Fe)dopedβ-Si_(3)N_(4) were investigated by First-principles calculations within CASTEP.The calculated lattice parameters ofβ-Si_(3)N_(4) were consistent with previous date.The cohesive energy and formation enthalpy show that initialβ-Si_(3)N_(4) has the highest structural stability.The calculated elastic constant and the Voigt-Reuss-Hill approximation indicate that elastic moduli ofβ-Si_(3)N_(4) are slightly reduced by M doping.Based on Poisson’s and Pugh’s ratio,β-Si_(3)N_(4) is a ductile material and the toughness ofβ-Si_(3)N_(4) increases with M doping,and Fe doping exhibited the best toughness.The results of density of states,charge distributions and overlapping populations indicate thatβ-Si_(3)N_(4) has the strong covalent and ionic bond strength between N and Si.
文摘Structural, electronic and optical properties of Sc-based aluminum-nitride alloy have been carried out with first-principles methods using both local density approximation (LDA) and Heyd-Scuseria-Ernzerhof (HSE) hybrid functional. This latter provides a more accurate description of the lattice parameters, enthalpy of formation, electronic and optical properties of our alloy than standard DFT. We found the transition from wurtzite to rocksalt structures at 61% of Sc concentration. By increasing the scandium concentration, the lattice parameters and the band gap decrease. The HSE band gap is in good agreement with available experimental data. The existence of the strong hybridization between Sc 3d and N 2p indicates the transport of electrons from Sc to N atoms. Besides, it is shown that the insertion of the Sc atom leads to the redshift of the optical absorption edge. The optical absorption of Sc<sub>x</sub>Al<sub>1-x</sub>N is found to decrease with increasing Sc concentrations in the low energy range. Because of this, Sc<sub>x</sub>Al<sub>1-x</sub>N have a great potential for applications in photovoltaics and photocatalysis.
文摘Rare earth luminescent materials have attracted significant attention due to their wide-ranging applications in the field of optoelectronics. This study aims to delve into the electronic structure and optical properties of rare earth luminescent materials, with the goal of uncovering their importance in luminescence mechanisms and applications. Through theoretical calculations and experimental methods, we conducted in-depth analyses on materials composed of various rare earth elements. Regarding electronic structure, we utilized computational techniques such as density functional theory to investigate the band structure, valence state distribution, and electronic density of states of rare earth luminescent materials. The results indicate that the electronic structural differences among different rare earth elements notably influence their luminescence performance, providing crucial clues for explaining the luminescence mechanism. In terms of optical properties, we systematically examined the material’s optical behaviors through fluorescence spectroscopy, absorption spectroscopy, and other experimental approaches. We found that rare earth luminescent materials exhibit distinct absorption and emission characteristics at different wavelengths, closely related to the transition processes of their electronic energy levels. Furthermore, we studied the influence of varying doping concentrations and impurities on the material’s optical properties. Experimental outcomes reveal that appropriate doping can effectively regulate the emission intensity and wavelength, offering greater possibilities for material applications. In summary, this study comprehensively analyzed the electronic structure and optical properties of rare earth luminescent materials, providing deep insights into understanding their luminescence mechanisms and potential value in optoelectronic applications. In the future, these research findings will serve as crucial references for the technological advancement in fields such as LEDs, lasers, and bioimaging.
基金Sponsored by the Science and Technology Foundation of Guizhou Province,China(Grant Nos.LH[2016]7077,LH[2015]7218)the Youth Science and Technology Talents Growth Fund Program of GuiZhou Province Education Department,China(Grant No.KY[2016]166)the Innovation Group Major Program of Guizhou Province(Grant Nos.KY[2016]028,KY[2016]029,KY[2016]030)
文摘A system study of the three-dimensional normal stress for regulating electronic structure and magnetic property of Fe_2Ge is studied. The density states of Fe more than 92% contribution come from Fe 3d,the density states of Ge mainly contributed from Ge 4p and Ge 4s,and the Fe 3d spin induces the Ge 4p electron transfer. The inductive effect increases germanium electron energy,weakens the Fe spin density of states,opposes the stability of the ferromagnetic state. The magnetic moment varies from 5 to 3 μB with the stress charges from-30 to 30 GPa. The charge of Fe is negative whereas the Ge atom is positively charged,the Fe atom loses charge,the charge transfers to the Ge atom. The unevenly distributed charge forms the newoccupy state and spin polarization state in the Fe_2Ge electron structure system. The Fe is the electron donor,the total electron is transferred to Ge,but the total numbers of gain electron and total numbers of lost electron are not equal,so the Fe_2Ge electron system may have hybridization between the Fe 3d state and Ge 4p state.The magnetic of Fe_2Ge mainly comes from the unoccupied Fe 3d orbital,the Fe 3d is positive spinpolarization state and the spin-polarization strength is decreased,the Ge 4p is negative spin-polarization state and the spin-polarization strength are increased. M oreover,electrons-spin polarization is relevant to the structure parameters of the Fe_2Ge system,and controls spin-polarized electronic behavior by means of adjusting ferromagnetic.
文摘Glycine is an active organic compound. It has been reported that it can be combined with H2SO4, HNO3, CaCl2 etc. to form single crystals. Recently, we have first found that NH2CH2COOH combined with H2C2O4 can form a new compound——glycine oxalate (the molecular formula is NH2CH4 COOH·H2C2O4). For simplicity, it is called GO. Growth and the properties of GO single crystal
文摘Ⅰ. INTRODUCTION Not long ago, we found that NH2CH2COOH could combine with H2C2O4 to form NH2CH2COOH·H2C2O4 single crystal which may be simply written as GO. In NH2CH2COOH—H2C2O4—H2O system, another new crystal, diglycine
文摘Using a new developed valence bond theory of intermetallic compound, the electronic structure and properties of TiAl were analysed systematically. It was determined that the valence electronic structure of Ti and Al atom in TiAl to be [ (4sf)0.42 (4sc) 1.36 (3dc)2.22]Ti and[ (3sf)0.39 (3sc)0.59 (3dc)2.02 ] Al respectively. According to these electronic structure, lattice constant, cohesive energy, potential curve, bulk modulus and temperature dependence of linear thermal expansion coefficient have been calculated, most of the theoretical values of these properties are in good agreement with experiment ones.
基金supported by the National Natural Science Foundation of China (E5057201)Heilongjiang Provincial Scientific and Technological Projects
文摘The electronic structure and optical properties of CdGeAs2 were calculated by the first principle method using ultra-soft pseudo-potential approach of the plane wave based upon density functional theory (DFT). Mulliken population analysis showed that atomic orbital hybridization occurs when forming chemical bonds. The relationship between inter-band transition and optical properties was analyzed to provide a theoretical basis for investigating or controlling CdGeAs2 crystal defects.
基金supported by the National Natural Science Foundation of China(21171039,21373048)the Open Foundation of Key Laboratory for High-energy Laser Science of China Academy of Engineering Physics(2012HCF05)
文摘The electronic structures and optical properties of II-III2-VI4 (II = Zn, Cd; III = In; VI = Se, Te) compounds are studied by the density functional theory (DFT) using the Vienna ab initio simulation package (VASP). Geometrical optimization of the unit cell is in good agreement with the experimental data. Our calculations show that the valence band maximum (VBM) and conduction band minimum (CBM) are located at G resulting in a direct energy gap. The optical properties are analyzed, and the independent second harmonic generation (SHG) coefficients are determined. By an analysis of the band structure, we can get that SHG response of the system can be attributed to the transitions from the bands near the top of valence band that are derived from the Se/Te p states to the unoccupied bands contributed by the p states of In atoms.
基金supported by the China Scholarship Council (CSC) and the National Natural Science Foundation of China (Grant Nos. 10676025 and 10574096)the Science-Technology Foundation for Young Scientist of Sichuan Province,China (Grant No. 09ZQ026-049)
文摘The systematic trends of electrionic structure and optical properties of rutile (P42/mnm) RuO2 have been cal- culated by using the plane-wave norm-conserving pseudopotential density functional theory (DFT) method within the generalised gradient approximation (GGA) for the exchange-correlation potential. The obtained equilibrium structure parameters are in excellent agreement with the experimental data. The calculated bulk modulus and elastic constants are also in good agreement with the experimental data and available theoretical calculations. Analysis based on elec- tronic structure and pseudogap reveals that the bonding nature in RuO2 is a combination of covalent, ionic and metallic bonds. Based on a Kramers Kronig analysis of the reflectivity, we have obtained the spectral dependence of the real and imaginary parts of the complex dielectric constant (~1 and z2, respectively) and the refractive index (n); and comparisons have shown that the theoretical results agree well with the experimental data as well. Meanwhile, we have also calculated the absorption coefficient, reflectivity index, electron energy loss function of RuO2 for radiation up to 30 eV. As a result, the predicted reflectivity index is in good agreement with the experimental data at low energies.
基金supported by the National Natural Science Foundation of China (No. 60937003)
文摘The systematic trends and effect introduced by Zr and C co-doping to TiO2 of electronic structure and optical properties of anatase TiO2 have been calculated by the plane-wave ultra-soft pseudopotential density functional theory (DFT) method within the generalized gradient approximation (GGA) for the exchange-correlation potential. Through the current calculations, the density of states (DOS), energy band structure and optical absorption coefficients have been obtained for TiO2 and compared with the doped TiO2, and the influence of electronic structure and optical properties caused by Zr and C co-doping has been presented qualitatively together. The results revealed that the energy band gap has been decreased owing to the doped Zr and C, whereas the optical absorption coefficients have been increased in the region of 400~800 nm and a red shift of absorption band can be found. Accordingly, photo catalytic activity of TiO2 has been enhanced. The current calculations are in good agreement with the experimental data.