Density(p)and speed of sound(u)findings on the binary liquid mixtures consisting of cyclohexanol(CH—OH),with aniline(A),ortho-chloroaniline(o-CA),and meta-chloroaniline(m-CA)were gathered at the various temperatures ...Density(p)and speed of sound(u)findings on the binary liquid mixtures consisting of cyclohexanol(CH—OH),with aniline(A),ortho-chloroaniline(o-CA),and meta-chloroaniline(m-CA)were gathered at the various temperatures spanning the entire concentration range.303.15,308.15,313.15 and 318.15 K at atmospheric pressure.The information measured there was utilized to compute excess molar volume(V_(m)^(E)),excess isentropic compressibility(K_(S)^(E)),excess of speed of sound(u^(F)),excess intermolecular free length(L_(f)^(F))and excess acoustic impedance(Z^(F)).Further,the partial molar volumes(^(-)V°_(m,1).^(-)V°_(φ,1).^(-)V°_(m,2).^(-)V°_(φ,2)),partial molar compressibilities(K°_(m,1).^(-)K°_(φ,1).^(-)K°_(m,2).^(-)K°_(φ,2))and their excess values(^(-)V^(E)_(m,1).^(-)V^(°E)_(φ,1).^(-)V^(E)_(m,2).^(-)V^(°E)_(φ,2)),(K^(E)_(m,1).^(-)K^(°E)_(φ,1).^(-)K^(E)_(m,2).^(-)K^(°E)_(φ,2))were also computed to perceive more information on molecular interaction and structural effects in these mixtures.Applying the theory of Prigogine-Flory-Patterson(PFP)as a framework,the V_(m)^(E)data of the current liquid mixtures were examined.The analysis of the experimental data took into consideration the interactions that occur between the individual molecules that make up liquid mixtures.By using density functional theory DFT(B3LYP)of 6-31++G(d,P)to analyze the geometries,bond characteristics,interaction energies,and hydrogen bonded complexes in organic solvent phase,quantum chemical calculations were able to further confirm the hydrogen bonding that predominates between cyclohexanol with aniline and chlorosubstituted anilines.展开更多
The rational design of Ni-based catalysts is essential due to their abundance and low cost for advancing sustainable energy technologies,particularly for water splitting and fuel cells.This study employs spinpolarized...The rational design of Ni-based catalysts is essential due to their abundance and low cost for advancing sustainable energy technologies,particularly for water splitting and fuel cells.This study employs spinpolarized density functional theory(DFT)to examine the influence of anchoring rare-earth elements on the γ-NiOOH lattice surface,aiming to identify the optimal catalytic site for the oxygen evolution reaction(OER)and oxygen reduction reaction(ORR).Following the identification of an appropriate active site through Ni vacancy,a rare earth element(REE_(1))is introduced as a dopant for single-atom catalysis(SACs).The structural,thermodynamic,and catalytic characteristics of all newly designed REE_(1)/γ-NiOOH catalysts have been extensively studied.Among the newly developed catalysts,Tb_(1)/γ-NiOOH exhibits the lowest OER overpotential of(0.36 V),while Ce_(1)/γ-NiOOH and Pr_(1)/γ-NiOOH also demonstrate excellent OER performance(0.51 and 0.41 V),respectively.Notably,Nd_(1)/γ-NiOOH and Pm_(1)/γ-NiOOH exhibit efficient ORR activity,with low overpotentials of(0.63 and 0.61 V)due to their balanced adsorption and desorption energies of intermediates.Bader charge analysis reveals strong electron donation from doped REE1to the surface.This study identified Ce_(1),Pr_(1),Nd_(1),and Tb_(1) anchoring catalysts as highly promising for water-splitting applications.Moreover,Nd_(1) and Pm_(1) doping markedly improve ORR performance,underscoring their promise for enhanced electrochemical applications in metal-air batteries.The catalytic performance of all newly developed catalysts was further evaluated using electronic descriptors.The catalytic performance was further assessed using the volcano curve and scaling relationships for the adsorbed intermediates.This study offers an extensive theoretical foundation for designing cost-effective and high-performance REE_(1)/γ-NiOOH electrocatalysts.展开更多
The structural, electronic, and optical properties of Cu2Zn1−xBaxSn1−ySiyS4 compounds have been calculated using GGA-PBE function within the framework of Density Functional Theory (DFT). In the present work, lattice p...The structural, electronic, and optical properties of Cu2Zn1−xBaxSn1−ySiyS4 compounds have been calculated using GGA-PBE function within the framework of Density Functional Theory (DFT). In the present work, lattice parameters remained the same, that is tetragonal crystal structure for 0% and 100% doping concentration. The electronic band gap of Cu2Zn1−xBaxSn1−ySiyS4 compounds has been gradually increased for continuous increment of doping concentration where the highest electronic band gap is 1.117 eV for Cu2BaSiS4 structure. Moreover, the band gap changes from direct to indirect band gap with the increase of doping concentration in the parent compound. The absorption coefficient has been found to be high (> 104 cm−1) in UV-region for all the doping concentration which makes the studied compound as a potential candidate of absorber layer in the UV detector. The theoretical study of the effect of double doping in the CZTS compound is very interesting for improving the quality of it and it would be a reference for the theoretical and experimental researchers.展开更多
The condensation of benzaldehyde, urea, and ethyl acetoacetate according to the procedure described by Biginelli was investigated at the B3LYP/6-31G（d）, B3LYP/6-31 ＋G（d,p）, and B3LYP/6-311＋G（3df,2p）//B3LYP/6-3...The condensation of benzaldehyde, urea, and ethyl acetoacetate according to the procedure described by Biginelli was investigated at the B3LYP/6-31G（d）, B3LYP/6-31 ＋G（d,p）, and B3LYP/6-311＋G（3df,2p）//B3LYP/6-31＋G（d,p） levels to explore the reaction mechanism. According to the mechanism proposed by Kappe, structures of five intermediates were optimized and four transition states were found. The calculation results proved that the mechanism proposed by Kappe is right.展开更多
The increasing production and usage of chlorinated paraffins(CPs) correspondently increase the amount of CPs that experience thermal processes. Our previous study revealed that a significant amount of medium-chain chl...The increasing production and usage of chlorinated paraffins(CPs) correspondently increase the amount of CPs that experience thermal processes. Our previous study revealed that a significant amount of medium-chain chlorinated paraffins(MCCPs), short-chain chlorinated paraffins(SCCPs) as well as aromatic and chlorinated polycyclic aromatic hydrocarbons(Cl-PAHs) were formed synergistically during the thermal decomposition of CP-52(a class of CP products).However, the transformation mechanisms of CP-52 to these compounds are still not very clear.This article presents a mechanistic analysis on the decomposition of CP-52 experimentally and theoretically. It was found that CP-52 initially undergoes dehydrochlorination and carbon chain cleavage and it transformed into chlorinated and unsaturated hydrocarbons. Cyclization and aromatization were the most accessible pathways at low temperatures(200–400°C), both of which produce mostly aromatic hydrocarbons. As the temperature exceeds 400°C, the hydrocarbons could decompose into small molecules, and the subsequent radical-induced reactions become the predominant pathways, leading to the formation of Cl-PAHs. The decomposition of CP-52 was investigated by using density functional theory and calculations demonstrating the feasibility and rationality of PCB and PCN formation from chlorobenzene. The results improve the understanding of the transformation processes from CP-52 to SCCPs and Cl-PAHs as well as provide data for reducing their emissions during thermal-related processes.展开更多
The plane-wave pseudopotential function method, based on density-functional theory, has been used to calculate the adsorption, electronic band structures, orbitals and optical absorption spectrum of [Fe（CN）6]^4- on ...The plane-wave pseudopotential function method, based on density-functional theory, has been used to calculate the adsorption, electronic band structures, orbitals and optical absorption spectrum of [Fe（CN）6]^4- on TiOz anatase（101） surface. Our calculations reveal that the surface-modified anatase system has large adsorption energy and a much narrower band gap. [Fe（CN）6]^4- adsorption on the （101） surface could lead to a large red shift of the anatase optical absorption threshold, which extends into a visible region significantly. The calculated results are in agreement with the experiment and other theoretical studies reasonably. It is very important for the understanding and further development ofphotovoltaic materials that are active under visible light.展开更多
Based on density functional theory(DFT)and basic structure models,the chemical reactions on the surface of vanadium-titanium based selective catalytic reduction(SCR)denitrification catalysts were summarized.Reasonable...Based on density functional theory(DFT)and basic structure models,the chemical reactions on the surface of vanadium-titanium based selective catalytic reduction(SCR)denitrification catalysts were summarized.Reasonable structural models(non-periodic and periodic structural models)are the basis of density functional calculations.A periodic structure model was more appropriate to represent the catalyst surface,and its theoretical calculation results were more comparable with the experimental results than a nonperiodic model.It is generally believed that the SCR mechanism where NH3 and NO react to produce N2 and H2 O follows an Eley-Rideal type mechanism.NH2 NO was found to be an important intermediate in the SCR reaction,with multiple production routes.Simultaneously,the effects of H2 O,SO2 and metal on SCR catalysts were also summarized.展开更多
An AB-and AA-stacked bilayer graphene sheet （BLG） under an electric field is investigated by ab initio calculation. The interlayer distance between the two layers, band structures, and atomic charges of the system a...An AB-and AA-stacked bilayer graphene sheet （BLG） under an electric field is investigated by ab initio calculation. The interlayer distance between the two layers, band structures, and atomic charges of the system are investigated in the presence of different electric fields normal to the BLG. The AB-stacked BLG is able to tune the bandgap into 0.234 eV with the increase of the external electronic field to 1 V/nm, however, the AA-stacked BLG is not sensitive to the external electric field. In both the cases, the spacing between the BLG slightly change in terms of the electric field. The charges in the AB-stacked BLG are increased with the increase of the electric field, which is considered to be the reason that causes the bandgap opening in the AB-stacked BLG.展开更多
Density functional theory （DFT） calculations are employed to investigate the structural and electronic properties of MoS6^- and MoS6 clusters. Generalized Koopmans＇ theorem is applied to predict the vertical detach...Density functional theory （DFT） calculations are employed to investigate the structural and electronic properties of MoS6^- and MoS6 clusters. Generalized Koopmans＇ theorem is applied to predict the vertical detachment energies and simulate the photoelectron spectra （PES）. Intriguingly, the terminal S2-, polysulfide S2^2- and S3^2- ligands simultaneously emerge in the lowest-energy structure of MoS6. Molecular orbital analyses are performed to analyze the chemical bonding in MoS6^-/0 clusters and elucidate their structural and electronic properties.展开更多
The synthesis of 5-substituted 1H-tetrazoles in n,n-dimethylformamide（DMF） with b-cyclodextrin（β-CD） as catalyst can get an excellent yield in short reaction time.The interaction of β-CD with p-chlorobenzonitril...The synthesis of 5-substituted 1H-tetrazoles in n,n-dimethylformamide（DMF） with b-cyclodextrin（β-CD） as catalyst can get an excellent yield in short reaction time.The interaction of β-CD with p-chlorobenzonitrile plays an important role in this process.This paper studies the complex of β-CD with p-chlorobenzonitrile using density functional theory（DFT） method.The minimum energy structure is investigated in water,DMF and DMSO.Hydrogen bonds are researched on the basis of natural bonding orbital（NBO） analysis.The relative position between p-chlorobenzonitrile and β-CD in DMF is confirmed by 1H nuclear magnetic resonance（1H NMR）.The data from 13 C and 15 N spectra indicate that more positive charges focus on the carbon atom of cyanogroup（C11） and more negative charges concentrate on the nitrogen atom of cyanogroup（N12） upon complexation.The results from frontier molecular orbitals and Mulliken charge reveal that β-CD catalyst improves the reactivity and electrophilicity of p-chlorobenzonitrile.Meanwhile,the functional group of p-chlorobenzonitrile is easier to be attacked by azide ions in the presence of β-CD as catalyst.展开更多
1,2-Benzothiazine derivatives methyl 3-methoxy-4-oxo-3,4-dihydro-2H-benzo[e] [1,2]thiazine-3-carboxylate 1,1-dioxide（1） and methyl 2-ethyl-3-hydroxy-4-oxo-3,4-dihydro-2Hbenzo[e][1,2]thiazine-3-carboxylate 1,1-dioxid...1,2-Benzothiazine derivatives methyl 3-methoxy-4-oxo-3,4-dihydro-2H-benzo[e] [1,2]thiazine-3-carboxylate 1,1-dioxide（1） and methyl 2-ethyl-3-hydroxy-4-oxo-3,4-dihydro-2Hbenzo[e][1,2]thiazine-3-carboxylate 1,1-dioxide（2） were synthesized, and characterized by spectroscopic techniques; 1H-NMR and infrared（IR） spectroscopy. Crystals of 1 and 2 were grown by slow evaporation of methanol and ethyl acetate, respectively and their crystal structures were investigated by single-crystal X-ray diffraction analysis. Geometric properties were calculated by the B3 LYP method of density functional theory（DFT） at the 6-31G＋（d） basis set to compare with the experimental data. Simulated properties were found in strong agreement with the experimental ones. Intermolecular forces have also been modeled in order to investigate the strength of packing and strong hydrogen bonding was observed in both compounds 1 and 2. Electronic properties such as Ionization Potential（IP）, Electron Affinities（EA） and coefficients of the highest occupied molecular orbital（HOMO） and the lowest unoccupied molecular orbital（LUMO） of com- pounds 1 and 2 were simulated for the first time.展开更多
Various viscosity-composition curves of polymer blends are summarized in eight groups. To represent these curves. 'sub-cluster equations' are derived on the basis of so called 'sub-cluster theoryThe essent...Various viscosity-composition curves of polymer blends are summarized in eight groups. To represent these curves. 'sub-cluster equations' are derived on the basis of so called 'sub-cluster theoryThe essential concepts of sub-cluster theory and the derivation of those 'Sub-cluster equations' are briefly introduced.展开更多
During the underground mining of coal resources,overlying rocks on the roof of excavated tunnels will be destroyed due to ground pressure,and as a result,part of them will break and fall into the tunnels.How to determ...During the underground mining of coal resources,overlying rocks on the roof of excavated tunnels will be destroyed due to ground pressure,and as a result,part of them will break and fall into the tunnels.How to determine the distribution of fractured areas and fissures presents a major problem for preserving the overlying aquifer.展开更多
Density functional theory （DFT） was applied to study the ground state geometries and isomerization processes of 1,1＇-binaphthalene-8,8＇-diol. Three isomers, denoted as ISO1, ISO2, and ISO3, were found, distinguish...Density functional theory （DFT） was applied to study the ground state geometries and isomerization processes of 1,1＇-binaphthalene-8,8＇-diol. Three isomers, denoted as ISO1, ISO2, and ISO3, were found, distinguished by different orientations of the OH groups, and each OH-orientational isomer has R- and S-enantiomer. The conformational stabilities of these isomers were investigated by tracking the energy change with respect to the ring-to-ring torsion. The inter-conversions between the three OH-orientational S-isomers were found to have quite low barriers owing to the nearly free rotation of OH groups around the O-C single bonds. The S-R enantiomerization of ISO1 and ISO2 can take place through the ring-ring torsion around the C1-C1/ single bond, either in the anti-rotation manner or in the syn-rotation manner. The barriers of the anti routes are lower than those of the corresponding syn routes by 87.95 and 75.04 kJ/mol. For the S-R enantiomerization of ISO3, only the anti route was found. The barriers for the anti route enantiomerizations of ISO1, ISO2, and ISO3 are 119.61, 120.43, and 121.59 kJ/mol, respectively. A parallel reaction mechanism via three anti enantiomerization routes was proposed for the racemization of 1,1＇-binaphthalene-8,8＇-diol.展开更多
1 Introduction Shale formations bear abundant mineral resource and*unconventional petroleum resource,and the unconventional petroleum resource that contain in the shale formation should be integrated and researched.
In order to study the characteristics of cold frontal motion over the arbitrary topography, the velocity of cold frontal movement is derived by using the one layer shallow-water model. The results show that there exis...In order to study the characteristics of cold frontal motion over the arbitrary topography, the velocity of cold frontal movement is derived by using the one layer shallow-water model. The results show that there exist the retardation in upwind side and rapid descent in the lee slope when the cold front crosses the topography.展开更多
On the basis of the three major rules of Skopos theory,the author of this thesis makes great efforts to make a contrastive study on the two Chinese versions of the famous novel Anne of Green Gables,illustrating mainly...On the basis of the three major rules of Skopos theory,the author of this thesis makes great efforts to make a contrastive study on the two Chinese versions of the famous novel Anne of Green Gables,illustrating mainly from the perspectives of paragraph,syntax,diction and rhetoric as well as notes and omission.展开更多
In 2014, 50 years following the introduction of density functional theory (DFT), a rigorous understanding of it was published [AIP Advances, 4, 127,104 (2014)]. This understanding includes two features that complete t...In 2014, 50 years following the introduction of density functional theory (DFT), a rigorous understanding of it was published [AIP Advances, 4, 127,104 (2014)]. This understanding includes two features that complete the theory in practice, inasmuch as they are necessary for its correct application in electronic structure calculations;this understanding elucidates what appears to have been the crucial misunderstanding for 50 years, namely, the confusion between a stationary solution, attainable with most basis sets, following self-consistent iterations, with the ground state solution. The latter is obtained by a calculation that employs the well-defined optimal basis set for the system. The aim of this work is to review the above understanding and to extend it to the relativistic generalization of density functional theory by Rajagopal and Callaway [Phys. Rev. B7, 1912 (1973)]. This extension straightforwardly follows similar steps taken in the non-relativistic case, with the four-component current density, in the former, replacing the electronic charge density, in the latter. This new understanding, which completes relativistic DFT in practice, is expected to be needed for the study of heavy atoms and of materials (from molecules to solids) containing them—as is the case for some high temperature superconductors.展开更多
文摘Density(p)and speed of sound(u)findings on the binary liquid mixtures consisting of cyclohexanol(CH—OH),with aniline(A),ortho-chloroaniline(o-CA),and meta-chloroaniline(m-CA)were gathered at the various temperatures spanning the entire concentration range.303.15,308.15,313.15 and 318.15 K at atmospheric pressure.The information measured there was utilized to compute excess molar volume(V_(m)^(E)),excess isentropic compressibility(K_(S)^(E)),excess of speed of sound(u^(F)),excess intermolecular free length(L_(f)^(F))and excess acoustic impedance(Z^(F)).Further,the partial molar volumes(^(-)V°_(m,1).^(-)V°_(φ,1).^(-)V°_(m,2).^(-)V°_(φ,2)),partial molar compressibilities(K°_(m,1).^(-)K°_(φ,1).^(-)K°_(m,2).^(-)K°_(φ,2))and their excess values(^(-)V^(E)_(m,1).^(-)V^(°E)_(φ,1).^(-)V^(E)_(m,2).^(-)V^(°E)_(φ,2)),(K^(E)_(m,1).^(-)K^(°E)_(φ,1).^(-)K^(E)_(m,2).^(-)K^(°E)_(φ,2))were also computed to perceive more information on molecular interaction and structural effects in these mixtures.Applying the theory of Prigogine-Flory-Patterson(PFP)as a framework,the V_(m)^(E)data of the current liquid mixtures were examined.The analysis of the experimental data took into consideration the interactions that occur between the individual molecules that make up liquid mixtures.By using density functional theory DFT(B3LYP)of 6-31++G(d,P)to analyze the geometries,bond characteristics,interaction energies,and hydrogen bonded complexes in organic solvent phase,quantum chemical calculations were able to further confirm the hydrogen bonding that predominates between cyclohexanol with aniline and chlorosubstituted anilines.
基金supported by the BRICS STI Framework Programme(No.52261145703)the Higher Education Discipline Innovation Project(National 111 Project,No.B16016)。
文摘The rational design of Ni-based catalysts is essential due to their abundance and low cost for advancing sustainable energy technologies,particularly for water splitting and fuel cells.This study employs spinpolarized density functional theory(DFT)to examine the influence of anchoring rare-earth elements on the γ-NiOOH lattice surface,aiming to identify the optimal catalytic site for the oxygen evolution reaction(OER)and oxygen reduction reaction(ORR).Following the identification of an appropriate active site through Ni vacancy,a rare earth element(REE_(1))is introduced as a dopant for single-atom catalysis(SACs).The structural,thermodynamic,and catalytic characteristics of all newly designed REE_(1)/γ-NiOOH catalysts have been extensively studied.Among the newly developed catalysts,Tb_(1)/γ-NiOOH exhibits the lowest OER overpotential of(0.36 V),while Ce_(1)/γ-NiOOH and Pr_(1)/γ-NiOOH also demonstrate excellent OER performance(0.51 and 0.41 V),respectively.Notably,Nd_(1)/γ-NiOOH and Pm_(1)/γ-NiOOH exhibit efficient ORR activity,with low overpotentials of(0.63 and 0.61 V)due to their balanced adsorption and desorption energies of intermediates.Bader charge analysis reveals strong electron donation from doped REE1to the surface.This study identified Ce_(1),Pr_(1),Nd_(1),and Tb_(1) anchoring catalysts as highly promising for water-splitting applications.Moreover,Nd_(1) and Pm_(1) doping markedly improve ORR performance,underscoring their promise for enhanced electrochemical applications in metal-air batteries.The catalytic performance of all newly developed catalysts was further evaluated using electronic descriptors.The catalytic performance was further assessed using the volcano curve and scaling relationships for the adsorbed intermediates.This study offers an extensive theoretical foundation for designing cost-effective and high-performance REE_(1)/γ-NiOOH electrocatalysts.
文摘The structural, electronic, and optical properties of Cu2Zn1−xBaxSn1−ySiyS4 compounds have been calculated using GGA-PBE function within the framework of Density Functional Theory (DFT). In the present work, lattice parameters remained the same, that is tetragonal crystal structure for 0% and 100% doping concentration. The electronic band gap of Cu2Zn1−xBaxSn1−ySiyS4 compounds has been gradually increased for continuous increment of doping concentration where the highest electronic band gap is 1.117 eV for Cu2BaSiS4 structure. Moreover, the band gap changes from direct to indirect band gap with the increase of doping concentration in the parent compound. The absorption coefficient has been found to be high (> 104 cm−1) in UV-region for all the doping concentration which makes the studied compound as a potential candidate of absorber layer in the UV detector. The theoretical study of the effect of double doping in the CZTS compound is very interesting for improving the quality of it and it would be a reference for the theoretical and experimental researchers.
文摘The condensation of benzaldehyde, urea, and ethyl acetoacetate according to the procedure described by Biginelli was investigated at the B3LYP/6-31G（d）, B3LYP/6-31 ＋G（d,p）, and B3LYP/6-311＋G（3df,2p）//B3LYP/6-31＋G（d,p） levels to explore the reaction mechanism. According to the mechanism proposed by Kappe, structures of five intermediates were optimized and four transition states were found. The calculation results proved that the mechanism proposed by Kappe is right.
基金supported by the National Natural Science Foundation of China (Nos.21625702,21337002,21621064)the National Basic Research Program of China (No.2015CB453102)the Strategic Priority Research Program of the Chinese Academy of Sciences (No.XDB14010400)
文摘The increasing production and usage of chlorinated paraffins(CPs) correspondently increase the amount of CPs that experience thermal processes. Our previous study revealed that a significant amount of medium-chain chlorinated paraffins(MCCPs), short-chain chlorinated paraffins(SCCPs) as well as aromatic and chlorinated polycyclic aromatic hydrocarbons(Cl-PAHs) were formed synergistically during the thermal decomposition of CP-52(a class of CP products).However, the transformation mechanisms of CP-52 to these compounds are still not very clear.This article presents a mechanistic analysis on the decomposition of CP-52 experimentally and theoretically. It was found that CP-52 initially undergoes dehydrochlorination and carbon chain cleavage and it transformed into chlorinated and unsaturated hydrocarbons. Cyclization and aromatization were the most accessible pathways at low temperatures(200–400°C), both of which produce mostly aromatic hydrocarbons. As the temperature exceeds 400°C, the hydrocarbons could decompose into small molecules, and the subsequent radical-induced reactions become the predominant pathways, leading to the formation of Cl-PAHs. The decomposition of CP-52 was investigated by using density functional theory and calculations demonstrating the feasibility and rationality of PCB and PCN formation from chlorobenzene. The results improve the understanding of the transformation processes from CP-52 to SCCPs and Cl-PAHs as well as provide data for reducing their emissions during thermal-related processes.
基金the Scientific and Technology Foundation of Fuzhou University and the Key Project of Fujian Province (2005HZ01-2-6)
文摘The plane-wave pseudopotential function method, based on density-functional theory, has been used to calculate the adsorption, electronic band structures, orbitals and optical absorption spectrum of [Fe（CN）6]^4- on TiOz anatase（101） surface. Our calculations reveal that the surface-modified anatase system has large adsorption energy and a much narrower band gap. [Fe（CN）6]^4- adsorption on the （101） surface could lead to a large red shift of the anatase optical absorption threshold, which extends into a visible region significantly. The calculated results are in agreement with the experiment and other theoretical studies reasonably. It is very important for the understanding and further development ofphotovoltaic materials that are active under visible light.
基金supported by the National Key Research&Development(R&D)Program of China(No.2017YFC0210500)the National Natural Science Foundation of China(No.51938014)
文摘Based on density functional theory(DFT)and basic structure models,the chemical reactions on the surface of vanadium-titanium based selective catalytic reduction(SCR)denitrification catalysts were summarized.Reasonable structural models(non-periodic and periodic structural models)are the basis of density functional calculations.A periodic structure model was more appropriate to represent the catalyst surface,and its theoretical calculation results were more comparable with the experimental results than a nonperiodic model.It is generally believed that the SCR mechanism where NH3 and NO react to produce N2 and H2 O follows an Eley-Rideal type mechanism.NH2 NO was found to be an important intermediate in the SCR reaction,with multiple production routes.Simultaneously,the effects of H2 O,SO2 and metal on SCR catalysts were also summarized.
基金Project supported by the National Natural Science Foundation of China (Grant No. 61176101)the "Zijing Program Foundation"of Zhejiang Universitythe Natural Science Foundation of Zhejiang Province for Oversea Returners
文摘An AB-and AA-stacked bilayer graphene sheet （BLG） under an electric field is investigated by ab initio calculation. The interlayer distance between the two layers, band structures, and atomic charges of the system are investigated in the presence of different electric fields normal to the BLG. The AB-stacked BLG is able to tune the bandgap into 0.234 eV with the increase of the external electronic field to 1 V/nm, however, the AA-stacked BLG is not sensitive to the external electric field. In both the cases, the spacing between the BLG slightly change in terms of the electric field. The charges in the AB-stacked BLG are increased with the increase of the electric field, which is considered to be the reason that causes the bandgap opening in the AB-stacked BLG.
基金Supported by the National Natural Science Foundation of China (21171039, 21073035, 21071031 and 90922022)National Science Foundation for Fostering Talents in Basic Research of the National Natural Science Foundation of China (J1103303)Foundation of Fuzhou University (0460-022342 and 0041-600616)
文摘Density functional theory （DFT） calculations are employed to investigate the structural and electronic properties of MoS6^- and MoS6 clusters. Generalized Koopmans＇ theorem is applied to predict the vertical detachment energies and simulate the photoelectron spectra （PES）. Intriguingly, the terminal S2-, polysulfide S2^2- and S3^2- ligands simultaneously emerge in the lowest-energy structure of MoS6. Molecular orbital analyses are performed to analyze the chemical bonding in MoS6^-/0 clusters and elucidate their structural and electronic properties.
基金supported by the Scientific Research Fund of Hunan Provincial Education Department(No.12A132)
文摘The synthesis of 5-substituted 1H-tetrazoles in n,n-dimethylformamide（DMF） with b-cyclodextrin（β-CD） as catalyst can get an excellent yield in short reaction time.The interaction of β-CD with p-chlorobenzonitrile plays an important role in this process.This paper studies the complex of β-CD with p-chlorobenzonitrile using density functional theory（DFT） method.The minimum energy structure is investigated in water,DMF and DMSO.Hydrogen bonds are researched on the basis of natural bonding orbital（NBO） analysis.The relative position between p-chlorobenzonitrile and β-CD in DMF is confirmed by 1H nuclear magnetic resonance（1H NMR）.The data from 13 C and 15 N spectra indicate that more positive charges focus on the carbon atom of cyanogroup（C11） and more negative charges concentrate on the nitrogen atom of cyanogroup（N12） upon complexation.The results from frontier molecular orbitals and Mulliken charge reveal that β-CD catalyst improves the reactivity and electrophilicity of p-chlorobenzonitrile.Meanwhile,the functional group of p-chlorobenzonitrile is easier to be attacked by azide ions in the presence of β-CD as catalyst.
基金funded by the Saudi Basic Industries Corporation(SABIC) and the Deanship of Scientific Research(DSR),King Abdulaziz University,Jeddah,under grant no.(MS/15/396/1434)
文摘1,2-Benzothiazine derivatives methyl 3-methoxy-4-oxo-3,4-dihydro-2H-benzo[e] [1,2]thiazine-3-carboxylate 1,1-dioxide（1） and methyl 2-ethyl-3-hydroxy-4-oxo-3,4-dihydro-2Hbenzo[e][1,2]thiazine-3-carboxylate 1,1-dioxide（2） were synthesized, and characterized by spectroscopic techniques; 1H-NMR and infrared（IR） spectroscopy. Crystals of 1 and 2 were grown by slow evaporation of methanol and ethyl acetate, respectively and their crystal structures were investigated by single-crystal X-ray diffraction analysis. Geometric properties were calculated by the B3 LYP method of density functional theory（DFT） at the 6-31G＋（d） basis set to compare with the experimental data. Simulated properties were found in strong agreement with the experimental ones. Intermolecular forces have also been modeled in order to investigate the strength of packing and strong hydrogen bonding was observed in both compounds 1 and 2. Electronic properties such as Ionization Potential（IP）, Electron Affinities（EA） and coefficients of the highest occupied molecular orbital（HOMO） and the lowest unoccupied molecular orbital（LUMO） of com- pounds 1 and 2 were simulated for the first time.
文摘Various viscosity-composition curves of polymer blends are summarized in eight groups. To represent these curves. 'sub-cluster equations' are derived on the basis of so called 'sub-cluster theoryThe essential concepts of sub-cluster theory and the derivation of those 'Sub-cluster equations' are briefly introduced.
基金supported by the State Key Program of National Natural Science of China(Grant No.41130637)
文摘During the underground mining of coal resources,overlying rocks on the roof of excavated tunnels will be destroyed due to ground pressure,and as a result,part of them will break and fall into the tunnels.How to determine the distribution of fractured areas and fissures presents a major problem for preserving the overlying aquifer.
文摘Density functional theory （DFT） was applied to study the ground state geometries and isomerization processes of 1,1＇-binaphthalene-8,8＇-diol. Three isomers, denoted as ISO1, ISO2, and ISO3, were found, distinguished by different orientations of the OH groups, and each OH-orientational isomer has R- and S-enantiomer. The conformational stabilities of these isomers were investigated by tracking the energy change with respect to the ring-to-ring torsion. The inter-conversions between the three OH-orientational S-isomers were found to have quite low barriers owing to the nearly free rotation of OH groups around the O-C single bonds. The S-R enantiomerization of ISO1 and ISO2 can take place through the ring-ring torsion around the C1-C1/ single bond, either in the anti-rotation manner or in the syn-rotation manner. The barriers of the anti routes are lower than those of the corresponding syn routes by 87.95 and 75.04 kJ/mol. For the S-R enantiomerization of ISO3, only the anti route was found. The barriers for the anti route enantiomerizations of ISO1, ISO2, and ISO3 are 119.61, 120.43, and 121.59 kJ/mol, respectively. A parallel reaction mechanism via three anti enantiomerization routes was proposed for the racemization of 1,1＇-binaphthalene-8,8＇-diol.
基金supported by funding the National Basic Research Program of China (973 Program) and the grant number is 2014CB239000
文摘1 Introduction Shale formations bear abundant mineral resource and*unconventional petroleum resource,and the unconventional petroleum resource that contain in the shale formation should be integrated and researched.
文摘In order to study the characteristics of cold frontal motion over the arbitrary topography, the velocity of cold frontal movement is derived by using the one layer shallow-water model. The results show that there exist the retardation in upwind side and rapid descent in the lee slope when the cold front crosses the topography.
文摘On the basis of the three major rules of Skopos theory,the author of this thesis makes great efforts to make a contrastive study on the two Chinese versions of the famous novel Anne of Green Gables,illustrating mainly from the perspectives of paragraph,syntax,diction and rhetoric as well as notes and omission.
文摘In 2014, 50 years following the introduction of density functional theory (DFT), a rigorous understanding of it was published [AIP Advances, 4, 127,104 (2014)]. This understanding includes two features that complete the theory in practice, inasmuch as they are necessary for its correct application in electronic structure calculations;this understanding elucidates what appears to have been the crucial misunderstanding for 50 years, namely, the confusion between a stationary solution, attainable with most basis sets, following self-consistent iterations, with the ground state solution. The latter is obtained by a calculation that employs the well-defined optimal basis set for the system. The aim of this work is to review the above understanding and to extend it to the relativistic generalization of density functional theory by Rajagopal and Callaway [Phys. Rev. B7, 1912 (1973)]. This extension straightforwardly follows similar steps taken in the non-relativistic case, with the four-component current density, in the former, replacing the electronic charge density, in the latter. This new understanding, which completes relativistic DFT in practice, is expected to be needed for the study of heavy atoms and of materials (from molecules to solids) containing them—as is the case for some high temperature superconductors.
