In nature,the properties of matter are ultimately governed by the electronic structures.Quantum chemistry(QC)at electronic level matches well with a few simple physical assumptions in solving simple problems.To date,m...In nature,the properties of matter are ultimately governed by the electronic structures.Quantum chemistry(QC)at electronic level matches well with a few simple physical assumptions in solving simple problems.To date,machine learning(ML)algorithm has been migrated to this field to simplify calculations and improve fidelity.This review introduces the basic information on universal electron structures of emerging energy materials and ML algorithms involved in the prediction of material properties.Then,the structure-property relationships based on ML algorithm and QC theory are reviewed.Especially,the summary of recently reported applications on classifying crystal structure,modeling electronic structure,optimizing experimental method,and predicting performance is provided.Last,an outlook on ML assisted QC calculation towards identifying emerging energy materials is also presented.展开更多
The formation process of aromatic hydrocarbon tar during the pyrolysis process of biomass components of cel-lulose and lignin was carried out by quantum chemical calculation based on density functional theory method B...The formation process of aromatic hydrocarbon tar during the pyrolysis process of biomass components of cel-lulose and lignin was carried out by quantum chemical calculation based on density functional theory method B3LYP/6-31G++(d,p).5 Hydroxymethylfurfural was chosen as the model compound of cellulose and hemicel-lulose,and syringa ldehyde was chosen as the model compound of lignin.The calculation results show that the formation process of cellulose monocyclic aromatic hydrocarbon tar is the conversion process of benzene ring from furan ring,and the highest reaction energy barrier appears in the process of decarbonylation,which is 370.8 kJ/mol.The formation of lignin monocyclic aromatic hydrocarbon tar is mainly the process of side chains removal and the formation of phenol,The highest reaction energy barrier appears in the process of decarbonyla-tion,which is 374.9 kJ/mol.The reaction mechanism of phenanthrene formation from naphthalene was selected as the formation of cellulose and lignin polycydic aromatic hydrocarbon tar.The calculation results show that he total barrier of the pathway that naphthalene dehydrogenates to form naphthalene free radicals and then reacts with ethylene twice by addition action,finally occurs cydization reactions and isomerizes to produce phenan-threne is lowest,that is 38.6 kJ/mol.So it is proved that the evolution of tar is the process of deoxygenation and cyclization with the increase of the temperature from a theoretical point of view.展开更多
The pyrolysis of 5-HMF was investigated using density functional theory methods at B3LYP/6-31 G++(d, p) level. Two possible pyrolytic pathways were proposed and full optimization of the energy gradient for the structu...The pyrolysis of 5-HMF was investigated using density functional theory methods at B3LYP/6-31 G++(d, p) level. Two possible pyrolytic pathways were proposed and full optimization of the energy gradient for the structures of reactants, products, intermediates and transition states of various reactions was implemented. The standard kinetic parameters in each reaction pathway were calculated and the formation and evolution mechanism of main pyrolysis products were analyzed. Bond dissociation energies calculation results show that the bond dissociation energy of CH_3—OH of 5-HMF is the lowest and the order of all kinds of bond dissociation energy is CH_3—OH<C—H<CH_3 OH—C_(aromatic)<CHO—C_(aromatic)<C_(aromatic)—H. In pathway(1), the energy barrier of furfural is 322.8 kJ/mol, the energy barrier of 2-furfuryl alcohol is 375.4 kJ/mol; the energy barrier of furan-2,5-dicarbaldehyde is 496.1 kJ/mol; the energy barrier of 5-methyl furfural is 375.8 kJ/mol, and the energy barrier of 2-methyl furan is 375.8 kJ/mol. In pathway(2), the activation energy required for open-loop with H_2O is higher.展开更多
Raman(resonance Raman,FT-Raman),IR and UV-visible spectroscopy and quantum chemistry calculations were used to investigate the photodissociation dynamics of furfural in S2 state.The resonance Raman(RR)spectra indicate...Raman(resonance Raman,FT-Raman),IR and UV-visible spectroscopy and quantum chemistry calculations were used to investigate the photodissociation dynamics of furfural in S2 state.The resonance Raman(RR)spectra indicate that the photorelaxation dynamics for the S0→S2 excited state is predominantly along nine motions:C=O stretchν5(1667 cm-1),ring C=C antisymmetric stretchν6(1570 cm-1),ring C=C symmetric stretchν7(1472 cm-1),C2-O6-C5 symmetric stretch/C1-H8 rock in planeν8(1389 cm-1),C3-C4 stretch/C1-H8 rock in planeν9(1370 cm-1),C5-O6 stretch in planeν12(1154 cm-1),ring breathν13(1077 cm-1),C3-C4 stretchν14(1020 cm-1),C3-C2-O6 symmetric stretchν16(928 cm-1).Stable structures of S0,S1,S2,T1 and T2 states with Cs point group were optimized at CASSCF method in Franck-Condon region there are S2/S1 conical intersection was found by state average method and RR spectra.展开更多
Two U0^(2+)_(2) complexes{[C_(5)H_(4)N(0)C=N-N=C(PhHPh)C=N-N=C(0)-C_(5)H_(4)N]2U02(CH30H)}(I)and{[C_(5)H_(4)N(0)ON-N=C(Ph)-(Ph)C=N-N=C(0)-C_(5)H_(4)N]2U02(C_(5)H_(4)N(0)C=N-NH_(2))}(II)were synthesized and characteriz...Two U0^(2+)_(2) complexes{[C_(5)H_(4)N(0)C=N-N=C(PhHPh)C=N-N=C(0)-C_(5)H_(4)N]2U02(CH30H)}(I)and{[C_(5)H_(4)N(0)ON-N=C(Ph)-(Ph)C=N-N=C(0)-C_(5)H_(4)N]2U02(C_(5)H_(4)N(0)C=N-NH_(2))}(II)were synthesized and characterized by IR,elemental analysis and thermal stability analysis,and the crystal structures were determined by X-ray diffraction.The crystal of complex I belongs to monoclinic system,space group P2_(1/n) with α=11.7678(4),6=16.9667(6),c=14.3051(5)A,β=98.918(3)°,Z=4,F=2821.64(17)A^(3),D_(c)=1.837 Mg·m^(-3),μ(MoKα)=5.805 mm^(-1),F(000)=1504,R=0.0346 and wR=0.0688.The crystal of complex II is of triclinic system,space group Pi with a=11.6417(5),b=11.7297(5),c=14.2197(5)A,α=71.697(4)°,β=86.020(3)°,γ=71.572(4)°,Z=2,K=1748.02(12)A^(3),D_(c)=1.742 Mg·m^(-3),μ(MoKa)=4.704 mm^(-1),F(000)=894,R=0.0283 and wR=0.0537.The U1 is a seven-coordinate pentagonal bipyramidal configuration in I and an eight-coordinate hexagonal dipyramidal configuration in II.The thermal stability and quantum chemical calculations of I and II were also investigated.展开更多
The surfaces of galena and pyrite,the adsorption of oxygen,and the reactions of ethyl xanthate on the sulfides were studied using quantum chemical calculations.In addition,the surface electron structures of the minera...The surfaces of galena and pyrite,the adsorption of oxygen,and the reactions of ethyl xanthate on the sulfides were studied using quantum chemical calculations.In addition,the surface electron structures of the minerals were discussed.According to the results,the mechanisms of ionic exchange reaction and dixanthogen adsorption for the xanthate notation of galena and pyrite were explained.The important role of oxygen in collector and collectorless flotation processes was also investigated.展开更多
The original variational quantum eigensolver(VQE)typically minimizes energy with hybrid quantum-classical optimization that aims to find the ground state.Here,we propose a VQE based on minimizing energy variance and c...The original variational quantum eigensolver(VQE)typically minimizes energy with hybrid quantum-classical optimization that aims to find the ground state.Here,we propose a VQE based on minimizing energy variance and call it the variance-VQE,which treats the ground state and excited states on the same footing,since an arbitrary eigenstate for a Hamiltonian should have zero energy variance.We demonstrate the properties of the variance-VQE for solving a set of excited states in quantum chemistry problems.Remarkably,we show that optimization of a combination of energy and variance may be more efficient to find low-energy excited states than those of minimizing energy or variance alone.We further reveal that the optimization can be boosted with stochastic gradient descent by Hamiltonian sampling,which uses only a few terms of the Hamiltonian and thus significantly reduces the quantum resource for evaluating variance and its gradients.展开更多
The electronic structure and the energy of various aluminate anions possibly existed in sodium aluminate solutions have been calculated by ah inilio and DV-Xct methods of quantum chemistry.The calculation results are ...The electronic structure and the energy of various aluminate anions possibly existed in sodium aluminate solutions have been calculated by ah inilio and DV-Xct methods of quantum chemistry.The calculation results are used to explain the experimental results of the spectroscopic study of sodium aluminate solutions.It has been found that Al(OH)4^(-)may be more stable than AlO_(2)in solutions,and that[(H0)3Al-O-Al(OH)_(3)]^(2-)may be more stable than[(HO)_(3)Al<H■H>Al(OH)_(3)]^(2-)anions.The ultraviolet spectra of sodium aluminate solutions are also interpreted by quantum chemical method.展开更多
tert-butanol and ethyl acetate,as fuel additives and oxygenated fuels,can improve fuels quality and reduce exhaust emissions.Therefore,the recovery of these compounds from azeotropic systems is of great significance.I...tert-butanol and ethyl acetate,as fuel additives and oxygenated fuels,can improve fuels quality and reduce exhaust emissions.Therefore,the recovery of these compounds from azeotropic systems is of great significance.Ionic liquids(ILs)are promising green solvents for separating azeotropic systems.In this study,an efficient extraction strategy based on 1-butyl-3-methylimidazolium acetate([Bmim][AC])is proposed.The mechanism by which ILs enable the separation of binary alcohol-ester azeotropes was revealed by evaluating the lowest conformational energy through combining an independent gradient model based on the Hirshfeld partition(IGMH)and frontier molecular orbitals,to preliminarily screen the extractants.The range of extractants was further reduced by a vapor–liquid phase equilibrium(VLE)experiment,and a modeling method for separating the alcohol–ester system and recovering the solvent using[Bmim][AC]and 1-ethyl-3-methyl-3-imidazolium acetate([Emim][AC])is established.Under the optimal operating conditions,the use of[Bmim][AC]can reduce the total annual cost(TAC)per year by 17.78%,and the emissions of CO_(2),SO_(2),and NO can be reduced by 10.86%.In this study,a comprehensive method for screening extractants is proposed,and the simulation process is optimized in combination with the economic and environmental impact.The results have important guiding significance for realizing efficient,energy-saving,and green azeotropic separation systems in industry.展开更多
A concise analytical model for the static dipole polarizability of ionized atoms and molecules is created for the first time.As input,it requires,alongside the polarizability of neutral counterpart of a given ion,only...A concise analytical model for the static dipole polarizability of ionized atoms and molecules is created for the first time.As input,it requires,alongside the polarizability of neutral counterpart of a given ion,only the charge and elemental composition.This physically motivated semiempirical model is based on a number of established regularities in polarizability of charged monatomic and polyatomic compounds.In order to adjust it,the results of quantum chemistry calculations and gas-phase measurements available for a broad range of ionized multielectron species are employed.To counteract the appreciable bias in the literature data toward polarizability of monoatomic ions,for some molecular ions of general concern the results of the authors'own density functional theory calculations are additionally invoked.A total of 541 data points are used to optimize the model.It is demonstrated that the model we suggested has reasonable(given the substantial uncertainties of the reference data)accuracy in predicting the static isotropic polarizability of arbitrarily charged ions of any size and atomic composition.The resulting polarizability estimates are found to achieve a coefficient of determination of 0.93 for the assembled data set.The created analytic tool is universally applicable and might be advantageous for some applications where there is an urgent need for rapid low-cost evaluation of the static gas-phase polarizability of ionized atoms and molecules.This is especially relevant to constructing the complex models of nonequilibrium chemical kinetics aimed at precisely describing the observable refractive index(dielectric permittivity)of plasma flows.The data sets that support the findings of this study are openly available in Science Data Bank at https://doi.org/10.57760/sciencedb.07526.展开更多
Bis(15-crown-5)-stilbenes containing crown ether parts have been widely used in a variety of chemical applications,such as cation detectors,because of their ability to selectively bind to alkali metal cations,Bis(15-c...Bis(15-crown-5)-stilbenes containing crown ether parts have been widely used in a variety of chemical applications,such as cation detectors,because of their ability to selectively bind to alkali metal cations,Bis(15-crown-5)-stilbenes and its derivatives with complexation of one-or two-alkali metal cation(Li^(+),Na^(+)and K^(+))have been theoretically investigat-ed by quantum chemistry methods.The coordination of alkali cations results in partial shrinkage of crown ethers,which directly affected natural distribution analysis charges and molecular orbital energy levels.The number of alkali metal ions has significant effects on absorption spectra and mean second hyperpolarizability.When one alkali metal ion was added to the anticonformer of bis(15-crown-5)-stilbene,the absorption spectra were obvious-ly redshifted and the mean second hyperpolarizability values were slightly increased;while two alkali metal ions were added to bis(15-crown-5)-stilbene,the absorption spectra were ob-viously blue shifted and the mean second hyperpolarizability values decreased.On the other hand,as the radius of the alkali ions increased,the mean second hyperpolarizability values of the compounds increased gradually.It is indicated that the mean second hyperpolarizability value is sensitive to the number and radius of the alkali metal cations,thus the third order nonlinear optical response can be used as a signal to detect the number and type of alkali met-al ions.展开更多
LLE data of cyclooctane/3-methylpentane + benzene/toluene + N-methylpyrrolidone (NMP) at 298.15 Kand 313.15 K under a pressure of 101.3 kPa were measured in this work. The Othmer-Tobias and Handequations were adopted ...LLE data of cyclooctane/3-methylpentane + benzene/toluene + N-methylpyrrolidone (NMP) at 298.15 Kand 313.15 K under a pressure of 101.3 kPa were measured in this work. The Othmer-Tobias and Handequations were adopted to validate the reliability of LLE data, where the correlation coefficients (R2) wereclose to unity, indicating the high reliability of the experimental data. The experimental data were analyzed using the distribution coefficient (D) and separation factor (S), and the effect of NMP extracting benzene and toluene from aromatics was explored. Meanwhile, the reason for the different extractionefficiencies of benzene and toluene using NMP was analyzed by quantum chemical calculations. TheNRTL and UNIQUAC thermodynamic models were used to correlate the liquid–liquid equilibrium data,and the relevant binary interaction parameters were obtained. The calculated root mean square deviation(RMSD) were all less than 0.0063, indicating that the obtained binary interaction parameters can be usedto simulate and calculate the extraction of aromatics using NMP.展开更多
We present a semiempirical analytical model for the static polarizability of electronically excited atoms and molecules,which requires very few readily accessible input data,including the ground-state polarizability,e...We present a semiempirical analytical model for the static polarizability of electronically excited atoms and molecules,which requires very few readily accessible input data,including the ground-state polarizability,elemental composition,ionization potential,and spin multiplicities of excited and ground states.This very simple model formulated in a semiclassical framework is based on a number of observed trends in polarizability of electronically excited compounds.To adjust the model,both accurate theoretical predictions and reliable measurements previously reported elsewhere for a broad range of multielectron species in the gas phase are utilized.For some representative compounds of general concern that have not yet attracted sufficient research interest,the results of our multireference second-order perturbation theory calculations are additionally engaged.We show that the model we developed has reasonable(given the considerable uncertainties in the reference data)accuracy in predicting the static polarizability of electronically excited species of arbitrary size and excitation energy.These findings can be useful for many applications,where there is a need for inexpensive and quick assessments of the static gas-phase polarizability of excited electronic states,in particular,when building the complex nonequilibrium kinetic models to describe the observed optical refractivity(dielectric permittivity)of nonthermal reacting gas flows.展开更多
The author list originally given in Wang et al. Chin. Phys. B 31 108702 (2022) has been amended to remove four authors, Hua Li, Bin Wu, Jun Guo and Chenqi Xu, who believe their contributions are more suitable to be cr...The author list originally given in Wang et al. Chin. Phys. B 31 108702 (2022) has been amended to remove four authors, Hua Li, Bin Wu, Jun Guo and Chenqi Xu, who believe their contributions are more suitable to be credited in the acknowledgments.展开更多
The charge distribution on Ni-Mo-S active sites can affect hydrodenitrogenation(HDN)activity.In this study,a series of model Ni-Mo-S were developed with various charge distributions.For comparison,the charge distribut...The charge distribution on Ni-Mo-S active sites can affect hydrodenitrogenation(HDN)activity.In this study,a series of model Ni-Mo-S were developed with various charge distributions.For comparison,the charge distribution effects on quinoline HDN were studied.The results show that a lack of electrons and extra protons can both lower the orbital eigenvalue of the Ni-Mo-S,leading to stronger adsorption of nitrogen-containing compounds and inhibition of ammonia desorption.Electron deficiency will improve the generation of active hydrogen on the active sites but inhibit hydrogen transfer to the nitrogen compounds;extra protons can provide H^(+)to the nitrogen compounds,which will flexibly transfer between the nitrogen compound and active sites,thus improving the cleavage of the C-N bond.展开更多
Gas adsorption has an important influence on gas flow in a coal body.Research on the characteristics of coal and gas adsorption is the theoretical basis for studying gas flow in coal.In this paper,the interaction betw...Gas adsorption has an important influence on gas flow in a coal body.Research on the characteristics of coal and gas adsorption is the theoretical basis for studying gas flow in coal.In this paper,the interaction between methane,carbon dioxide and surface molecules of anthracite was simulated using the quantum chemistry method.Adsorption energy and adsorption configurations of different quantities of gas molecules absorbed on the coal surface were calculated.The results show that adsorption between coal and the two kinds of gas molecules is a physical adsorption process and there is an optimal configuration.Gas molecules are more easily adsorbed in the hydroxyl-containing side chain,while it is difficult for them to be adsorbed at the position of the benzene ring.Besides,carbon dioxide molecules are more readily adsorbed on the coal surface than methane molecules.The findings have an important significance in revealing the nature of gas adsorption in coal.展开更多
The stable configurations and hydrogen bond nature of (H2O)n clusters (n = 3～6) have been investigated by the B3LYP method at the 6-31++g** level. Upon calculation, four conclusions have been drawn: (1) In the (H2O)3...The stable configurations and hydrogen bond nature of (H2O)n clusters (n = 3～6) have been investigated by the B3LYP method at the 6-31++g** level. Upon calculation, four conclusions have been drawn: (1) In the (H2O)3～5 clusters, cyclic configurations were confirmed to be the most stable. But in the (H2O)3～4 ones, only cyclic configurations could be observed. From n = 5 ((H2O)5 clusters), three-dimensional configuration could be found; (2) In the (H2O)6 clusters, all configurations are inclined to be three-dimensional except the most stable configuration which is cyclic; (3) The stable order of (H2O)6 clusters indicates that it is the arrangement of hydrogen bond that plays a decisive role in the cluster stabilities, the zero-point energy is also important, and cluster stabilities are independent on the number of hydrogen bonds; (4) There exist strong cooperativity and superadditivity in the (H2O)n clusters.展开更多
The chlorine(Cl2)drying technology using ionic liquids(ILs)as absorbents was proposed for the first time and systematically investigated from the molecular level scaled up to the industrial level.The hygroscopic IL[EM...The chlorine(Cl2)drying technology using ionic liquids(ILs)as absorbents was proposed for the first time and systematically investigated from the molecular level scaled up to the industrial level.The hygroscopic IL[EMIM][CH3SO3]was screened as a suitable absorbent from 238 potential IL candidates consisting of 14 cations and 17 anions,by calculating the Cl2 and H2O solubility and separation selectivity of Cl2 to H2O in different ILs based on the COSMO-RS model.The microscopic atomic and molecular insights into the separation mechanisms were deeply revealed by using COSMO-RS model analyses(i.e.,σ-profiles,σ-potentials,excess enthalpies,entropies,and Gibbs free energies)and quantum chemistry calculation(binding energies and weak interaction analyses).The Cl2 solubility in pure IL and H2O+IL systems were predicted by the COSMO-RS model,and the results agree with the microscopic mechanism identification.Moreover,the strict equilibrium stage model employed with the COSMO-RS model parameters was built to perform the process simulation,and continuous Cl2 drying with ILs was conceptually designed and optimized at industrial scale.It was confirmed that[EMIM][CH3SO3]is a very promising absorbent leading to a less IL amount,a much lower energy consumption than the other IL[EMIM][BF4],which has a very bright industrialization potential used for Cl2 drying technology.展开更多
Malaria is a real public health problem. It’s one of the pathologies that mobilize the scientific community. Resistance to existing treatments is the basis for the search for new treatments. Some molecules such as Ma...Malaria is a real public health problem. It’s one of the pathologies that mobilize the scientific community. Resistance to existing treatments is the basis for the search for new treatments. Some molecules such as Manzamenones have shown important antimalarial properties. These molecules belong to the family of atypical fatty acid derivatives. This work presents the relative stabilities, some reactivity properties and the privileged sites of interaction by hydrogen bond of fourteen Manzamenones and two antimalarial drugs: quinine and Artemisinin. These analyses were performed using quantum chemical calculations. We employed the two-layer ONIOM calculation method;namely ONIOM (B3LYP/6-311++G (d, p): AM1) for the fourteen Manzamenones. The geometries of the two antimalarials are calculated at B3LYP/6-311++G (d, p). The electrostatic potential (ESP) calculation of all molecules is done at the B3LYP/6-31++G (d, p) level. The formation processes of the molecules are discussed from the thermodynamic quantities we have calculated. The relative stabilities, the energies of the frontier orbitals, the energy gaps, the dipole moment, etc., are evaluated and discussed. The electrostatic potential at the molecular surface has been used to identify the sites favorable to the formation of hydrogen bonds.展开更多
基金supported by the National Natural Science Foundation of China(grant number 51872157)Shenzhen Technical Plan Project(grant number KQJSCX20160226191136 and JCYJ20170412170911187)Research Grants Council of the Hong Kong Special Administrative Region,China[grant number PF17-10186]。
文摘In nature,the properties of matter are ultimately governed by the electronic structures.Quantum chemistry(QC)at electronic level matches well with a few simple physical assumptions in solving simple problems.To date,machine learning(ML)algorithm has been migrated to this field to simplify calculations and improve fidelity.This review introduces the basic information on universal electron structures of emerging energy materials and ML algorithms involved in the prediction of material properties.Then,the structure-property relationships based on ML algorithm and QC theory are reviewed.Especially,the summary of recently reported applications on classifying crystal structure,modeling electronic structure,optimizing experimental method,and predicting performance is provided.Last,an outlook on ML assisted QC calculation towards identifying emerging energy materials is also presented.
基金supported by 2021–2022 Hunan Province Enterprise Science and Technology Commissioner Program Project under the Contract No.2021GK5046the project supported by Scientific Research Fund of Hunan Provincial Education Department under the Contract No.19C0476the project supported by Scientific Research Fund of Hunan Institute of Engineering under the Contract No.XJ1902.
文摘The formation process of aromatic hydrocarbon tar during the pyrolysis process of biomass components of cel-lulose and lignin was carried out by quantum chemical calculation based on density functional theory method B3LYP/6-31G++(d,p).5 Hydroxymethylfurfural was chosen as the model compound of cellulose and hemicel-lulose,and syringa ldehyde was chosen as the model compound of lignin.The calculation results show that the formation process of cellulose monocyclic aromatic hydrocarbon tar is the conversion process of benzene ring from furan ring,and the highest reaction energy barrier appears in the process of decarbonylation,which is 370.8 kJ/mol.The formation of lignin monocyclic aromatic hydrocarbon tar is mainly the process of side chains removal and the formation of phenol,The highest reaction energy barrier appears in the process of decarbonyla-tion,which is 374.9 kJ/mol.The reaction mechanism of phenanthrene formation from naphthalene was selected as the formation of cellulose and lignin polycydic aromatic hydrocarbon tar.The calculation results show that he total barrier of the pathway that naphthalene dehydrogenates to form naphthalene free radicals and then reacts with ethylene twice by addition action,finally occurs cydization reactions and isomerizes to produce phenan-threne is lowest,that is 38.6 kJ/mol.So it is proved that the evolution of tar is the process of deoxygenation and cyclization with the increase of the temperature from a theoretical point of view.
基金Project(51276023)supported by the National Natural Science Foundation of China
文摘The pyrolysis of 5-HMF was investigated using density functional theory methods at B3LYP/6-31 G++(d, p) level. Two possible pyrolytic pathways were proposed and full optimization of the energy gradient for the structures of reactants, products, intermediates and transition states of various reactions was implemented. The standard kinetic parameters in each reaction pathway were calculated and the formation and evolution mechanism of main pyrolysis products were analyzed. Bond dissociation energies calculation results show that the bond dissociation energy of CH_3—OH of 5-HMF is the lowest and the order of all kinds of bond dissociation energy is CH_3—OH<C—H<CH_3 OH—C_(aromatic)<CHO—C_(aromatic)<C_(aromatic)—H. In pathway(1), the energy barrier of furfural is 322.8 kJ/mol, the energy barrier of 2-furfuryl alcohol is 375.4 kJ/mol; the energy barrier of furan-2,5-dicarbaldehyde is 496.1 kJ/mol; the energy barrier of 5-methyl furfural is 375.8 kJ/mol, and the energy barrier of 2-methyl furan is 375.8 kJ/mol. In pathway(2), the activation energy required for open-loop with H_2O is higher.
基金This work was supported in parts by National Natural Science Foundation of China(No.21673208)Zhejiang Provincial Natural Science Foundation of China(No.LY16B070009).
文摘Raman(resonance Raman,FT-Raman),IR and UV-visible spectroscopy and quantum chemistry calculations were used to investigate the photodissociation dynamics of furfural in S2 state.The resonance Raman(RR)spectra indicate that the photorelaxation dynamics for the S0→S2 excited state is predominantly along nine motions:C=O stretchν5(1667 cm-1),ring C=C antisymmetric stretchν6(1570 cm-1),ring C=C symmetric stretchν7(1472 cm-1),C2-O6-C5 symmetric stretch/C1-H8 rock in planeν8(1389 cm-1),C3-C4 stretch/C1-H8 rock in planeν9(1370 cm-1),C5-O6 stretch in planeν12(1154 cm-1),ring breathν13(1077 cm-1),C3-C4 stretchν14(1020 cm-1),C3-C2-O6 symmetric stretchν16(928 cm-1).Stable structures of S0,S1,S2,T1 and T2 states with Cs point group were optimized at CASSCF method in Franck-Condon region there are S2/S1 conical intersection was found by state average method and RR spectra.
基金Supported by the Foundation of Hunan Provincial Engineering Research Center for Uranium Exploration Technology(No.YK20K03)。
文摘Two U0^(2+)_(2) complexes{[C_(5)H_(4)N(0)C=N-N=C(PhHPh)C=N-N=C(0)-C_(5)H_(4)N]2U02(CH30H)}(I)and{[C_(5)H_(4)N(0)ON-N=C(Ph)-(Ph)C=N-N=C(0)-C_(5)H_(4)N]2U02(C_(5)H_(4)N(0)C=N-NH_(2))}(II)were synthesized and characterized by IR,elemental analysis and thermal stability analysis,and the crystal structures were determined by X-ray diffraction.The crystal of complex I belongs to monoclinic system,space group P2_(1/n) with α=11.7678(4),6=16.9667(6),c=14.3051(5)A,β=98.918(3)°,Z=4,F=2821.64(17)A^(3),D_(c)=1.837 Mg·m^(-3),μ(MoKα)=5.805 mm^(-1),F(000)=1504,R=0.0346 and wR=0.0688.The crystal of complex II is of triclinic system,space group Pi with a=11.6417(5),b=11.7297(5),c=14.2197(5)A,α=71.697(4)°,β=86.020(3)°,γ=71.572(4)°,Z=2,K=1748.02(12)A^(3),D_(c)=1.742 Mg·m^(-3),μ(MoKa)=4.704 mm^(-1),F(000)=894,R=0.0283 and wR=0.0537.The U1 is a seven-coordinate pentagonal bipyramidal configuration in I and an eight-coordinate hexagonal dipyramidal configuration in II.The thermal stability and quantum chemical calculations of I and II were also investigated.
文摘The surfaces of galena and pyrite,the adsorption of oxygen,and the reactions of ethyl xanthate on the sulfides were studied using quantum chemical calculations.In addition,the surface electron structures of the minerals were discussed.According to the results,the mechanisms of ionic exchange reaction and dixanthogen adsorption for the xanthate notation of galena and pyrite were explained.The important role of oxygen in collector and collectorless flotation processes was also investigated.
基金supported by the National Natural Science Foundation of China(Grant No.12005065)the Guangdong Basic and Applied Basic Research Fund(Grant No.2021A1515010317)
文摘The original variational quantum eigensolver(VQE)typically minimizes energy with hybrid quantum-classical optimization that aims to find the ground state.Here,we propose a VQE based on minimizing energy variance and call it the variance-VQE,which treats the ground state and excited states on the same footing,since an arbitrary eigenstate for a Hamiltonian should have zero energy variance.We demonstrate the properties of the variance-VQE for solving a set of excited states in quantum chemistry problems.Remarkably,we show that optimization of a combination of energy and variance may be more efficient to find low-energy excited states than those of minimizing energy or variance alone.We further reveal that the optimization can be boosted with stochastic gradient descent by Hamiltonian sampling,which uses only a few terms of the Hamiltonian and thus significantly reduces the quantum resource for evaluating variance and its gradients.
基金supported by the National Natural Science Foundation of China。
文摘The electronic structure and the energy of various aluminate anions possibly existed in sodium aluminate solutions have been calculated by ah inilio and DV-Xct methods of quantum chemistry.The calculation results are used to explain the experimental results of the spectroscopic study of sodium aluminate solutions.It has been found that Al(OH)4^(-)may be more stable than AlO_(2)in solutions,and that[(H0)3Al-O-Al(OH)_(3)]^(2-)may be more stable than[(HO)_(3)Al<H■H>Al(OH)_(3)]^(2-)anions.The ultraviolet spectra of sodium aluminate solutions are also interpreted by quantum chemical method.
基金National Natural Science Foundation of China(22078166)Taishan Scholar Constructive Engineering Foundation(tsqn202211163).
文摘tert-butanol and ethyl acetate,as fuel additives and oxygenated fuels,can improve fuels quality and reduce exhaust emissions.Therefore,the recovery of these compounds from azeotropic systems is of great significance.Ionic liquids(ILs)are promising green solvents for separating azeotropic systems.In this study,an efficient extraction strategy based on 1-butyl-3-methylimidazolium acetate([Bmim][AC])is proposed.The mechanism by which ILs enable the separation of binary alcohol-ester azeotropes was revealed by evaluating the lowest conformational energy through combining an independent gradient model based on the Hirshfeld partition(IGMH)and frontier molecular orbitals,to preliminarily screen the extractants.The range of extractants was further reduced by a vapor–liquid phase equilibrium(VLE)experiment,and a modeling method for separating the alcohol–ester system and recovering the solvent using[Bmim][AC]and 1-ethyl-3-methyl-3-imidazolium acetate([Emim][AC])is established.Under the optimal operating conditions,the use of[Bmim][AC]can reduce the total annual cost(TAC)per year by 17.78%,and the emissions of CO_(2),SO_(2),and NO can be reduced by 10.86%.In this study,a comprehensive method for screening extractants is proposed,and the simulation process is optimized in combination with the economic and environmental impact.The results have important guiding significance for realizing efficient,energy-saving,and green azeotropic separation systems in industry.
基金Project supported by the grant of the Russian Science Foundation(Project No.22-29-00124)。
文摘A concise analytical model for the static dipole polarizability of ionized atoms and molecules is created for the first time.As input,it requires,alongside the polarizability of neutral counterpart of a given ion,only the charge and elemental composition.This physically motivated semiempirical model is based on a number of established regularities in polarizability of charged monatomic and polyatomic compounds.In order to adjust it,the results of quantum chemistry calculations and gas-phase measurements available for a broad range of ionized multielectron species are employed.To counteract the appreciable bias in the literature data toward polarizability of monoatomic ions,for some molecular ions of general concern the results of the authors'own density functional theory calculations are additionally invoked.A total of 541 data points are used to optimize the model.It is demonstrated that the model we suggested has reasonable(given the substantial uncertainties of the reference data)accuracy in predicting the static isotropic polarizability of arbitrarily charged ions of any size and atomic composition.The resulting polarizability estimates are found to achieve a coefficient of determination of 0.93 for the assembled data set.The created analytic tool is universally applicable and might be advantageous for some applications where there is an urgent need for rapid low-cost evaluation of the static gas-phase polarizability of ionized atoms and molecules.This is especially relevant to constructing the complex models of nonequilibrium chemical kinetics aimed at precisely describing the observable refractive index(dielectric permittivity)of plasma flows.The data sets that support the findings of this study are openly available in Science Data Bank at https://doi.org/10.57760/sciencedb.07526.
基金surported by the Jilin Province Science and Technology Development Project(No.20220203017SF)Industrialization Project of the 13th Five-Year"Education Department of Jilin Province(No.JJKH20200334KJ)the National Natural Sci-ence Foundation of China(No.11704143).
文摘Bis(15-crown-5)-stilbenes containing crown ether parts have been widely used in a variety of chemical applications,such as cation detectors,because of their ability to selectively bind to alkali metal cations,Bis(15-crown-5)-stilbenes and its derivatives with complexation of one-or two-alkali metal cation(Li^(+),Na^(+)and K^(+))have been theoretically investigat-ed by quantum chemistry methods.The coordination of alkali cations results in partial shrinkage of crown ethers,which directly affected natural distribution analysis charges and molecular orbital energy levels.The number of alkali metal ions has significant effects on absorption spectra and mean second hyperpolarizability.When one alkali metal ion was added to the anticonformer of bis(15-crown-5)-stilbene,the absorption spectra were obvious-ly redshifted and the mean second hyperpolarizability values were slightly increased;while two alkali metal ions were added to bis(15-crown-5)-stilbene,the absorption spectra were ob-viously blue shifted and the mean second hyperpolarizability values decreased.On the other hand,as the radius of the alkali ions increased,the mean second hyperpolarizability values of the compounds increased gradually.It is indicated that the mean second hyperpolarizability value is sensitive to the number and radius of the alkali metal cations,thus the third order nonlinear optical response can be used as a signal to detect the number and type of alkali met-al ions.
基金the National Natural Science Foundation of China(22178190)the National Youth Natural Science Foundation of China(CN)(22008129).
文摘LLE data of cyclooctane/3-methylpentane + benzene/toluene + N-methylpyrrolidone (NMP) at 298.15 Kand 313.15 K under a pressure of 101.3 kPa were measured in this work. The Othmer-Tobias and Handequations were adopted to validate the reliability of LLE data, where the correlation coefficients (R2) wereclose to unity, indicating the high reliability of the experimental data. The experimental data were analyzed using the distribution coefficient (D) and separation factor (S), and the effect of NMP extracting benzene and toluene from aromatics was explored. Meanwhile, the reason for the different extractionefficiencies of benzene and toluene using NMP was analyzed by quantum chemical calculations. TheNRTL and UNIQUAC thermodynamic models were used to correlate the liquid–liquid equilibrium data,and the relevant binary interaction parameters were obtained. The calculated root mean square deviation(RMSD) were all less than 0.0063, indicating that the obtained binary interaction parameters can be usedto simulate and calculate the extraction of aromatics using NMP.
基金supported by the grant of the Russian Science Foundation(project No.22-29-00124)。
文摘We present a semiempirical analytical model for the static polarizability of electronically excited atoms and molecules,which requires very few readily accessible input data,including the ground-state polarizability,elemental composition,ionization potential,and spin multiplicities of excited and ground states.This very simple model formulated in a semiclassical framework is based on a number of observed trends in polarizability of electronically excited compounds.To adjust the model,both accurate theoretical predictions and reliable measurements previously reported elsewhere for a broad range of multielectron species in the gas phase are utilized.For some representative compounds of general concern that have not yet attracted sufficient research interest,the results of our multireference second-order perturbation theory calculations are additionally engaged.We show that the model we developed has reasonable(given the considerable uncertainties in the reference data)accuracy in predicting the static polarizability of electronically excited species of arbitrary size and excitation energy.These findings can be useful for many applications,where there is a need for inexpensive and quick assessments of the static gas-phase polarizability of excited electronic states,in particular,when building the complex nonequilibrium kinetic models to describe the observed optical refractivity(dielectric permittivity)of nonthermal reacting gas flows.
文摘The author list originally given in Wang et al. Chin. Phys. B 31 108702 (2022) has been amended to remove four authors, Hua Li, Bin Wu, Jun Guo and Chenqi Xu, who believe their contributions are more suitable to be credited in the acknowledgments.
基金the financial support from the Sinopec Science and Technology Department(Grant No.121014-1)。
文摘The charge distribution on Ni-Mo-S active sites can affect hydrodenitrogenation(HDN)activity.In this study,a series of model Ni-Mo-S were developed with various charge distributions.For comparison,the charge distribution effects on quinoline HDN were studied.The results show that a lack of electrons and extra protons can both lower the orbital eigenvalue of the Ni-Mo-S,leading to stronger adsorption of nitrogen-containing compounds and inhibition of ammonia desorption.Electron deficiency will improve the generation of active hydrogen on the active sites but inhibit hydrogen transfer to the nitrogen compounds;extra protons can provide H^(+)to the nitrogen compounds,which will flexibly transfer between the nitrogen compound and active sites,thus improving the cleavage of the C-N bond.
基金foundation by the National Key Basic Research and Development Project Program of China(No.2011CB201202-2)the Research Fund for the Doctoral Program of Higher Education(No.20120023120005)+1 种基金the Foundation of State Key Laboratory of Coal Resources and Safety Mining(No.SKLCRSM11KFB04)the Fundamental Research Funds for the Central Universities(No.2009kz03)
文摘Gas adsorption has an important influence on gas flow in a coal body.Research on the characteristics of coal and gas adsorption is the theoretical basis for studying gas flow in coal.In this paper,the interaction between methane,carbon dioxide and surface molecules of anthracite was simulated using the quantum chemistry method.Adsorption energy and adsorption configurations of different quantities of gas molecules absorbed on the coal surface were calculated.The results show that adsorption between coal and the two kinds of gas molecules is a physical adsorption process and there is an optimal configuration.Gas molecules are more easily adsorbed in the hydroxyl-containing side chain,while it is difficult for them to be adsorbed at the position of the benzene ring.Besides,carbon dioxide molecules are more readily adsorbed on the coal surface than methane molecules.The findings have an important significance in revealing the nature of gas adsorption in coal.
基金Project supported by the Natural Science Foundation of Tangshan Teacher’s College (No. 04C06)
文摘The stable configurations and hydrogen bond nature of (H2O)n clusters (n = 3～6) have been investigated by the B3LYP method at the 6-31++g** level. Upon calculation, four conclusions have been drawn: (1) In the (H2O)3～5 clusters, cyclic configurations were confirmed to be the most stable. But in the (H2O)3～4 ones, only cyclic configurations could be observed. From n = 5 ((H2O)5 clusters), three-dimensional configuration could be found; (2) In the (H2O)6 clusters, all configurations are inclined to be three-dimensional except the most stable configuration which is cyclic; (3) The stable order of (H2O)6 clusters indicates that it is the arrangement of hydrogen bond that plays a decisive role in the cluster stabilities, the zero-point energy is also important, and cluster stabilities are independent on the number of hydrogen bonds; (4) There exist strong cooperativity and superadditivity in the (H2O)n clusters.
基金financially supported by the National Postdoctoral Program for Innovative Talents(BX20190021)the National Natural Science Foundation of China(No.22008003)
文摘The chlorine(Cl2)drying technology using ionic liquids(ILs)as absorbents was proposed for the first time and systematically investigated from the molecular level scaled up to the industrial level.The hygroscopic IL[EMIM][CH3SO3]was screened as a suitable absorbent from 238 potential IL candidates consisting of 14 cations and 17 anions,by calculating the Cl2 and H2O solubility and separation selectivity of Cl2 to H2O in different ILs based on the COSMO-RS model.The microscopic atomic and molecular insights into the separation mechanisms were deeply revealed by using COSMO-RS model analyses(i.e.,σ-profiles,σ-potentials,excess enthalpies,entropies,and Gibbs free energies)and quantum chemistry calculation(binding energies and weak interaction analyses).The Cl2 solubility in pure IL and H2O+IL systems were predicted by the COSMO-RS model,and the results agree with the microscopic mechanism identification.Moreover,the strict equilibrium stage model employed with the COSMO-RS model parameters was built to perform the process simulation,and continuous Cl2 drying with ILs was conceptually designed and optimized at industrial scale.It was confirmed that[EMIM][CH3SO3]is a very promising absorbent leading to a less IL amount,a much lower energy consumption than the other IL[EMIM][BF4],which has a very bright industrialization potential used for Cl2 drying technology.
文摘Malaria is a real public health problem. It’s one of the pathologies that mobilize the scientific community. Resistance to existing treatments is the basis for the search for new treatments. Some molecules such as Manzamenones have shown important antimalarial properties. These molecules belong to the family of atypical fatty acid derivatives. This work presents the relative stabilities, some reactivity properties and the privileged sites of interaction by hydrogen bond of fourteen Manzamenones and two antimalarial drugs: quinine and Artemisinin. These analyses were performed using quantum chemical calculations. We employed the two-layer ONIOM calculation method;namely ONIOM (B3LYP/6-311++G (d, p): AM1) for the fourteen Manzamenones. The geometries of the two antimalarials are calculated at B3LYP/6-311++G (d, p). The electrostatic potential (ESP) calculation of all molecules is done at the B3LYP/6-31++G (d, p) level. The formation processes of the molecules are discussed from the thermodynamic quantities we have calculated. The relative stabilities, the energies of the frontier orbitals, the energy gaps, the dipole moment, etc., are evaluated and discussed. The electrostatic potential at the molecular surface has been used to identify the sites favorable to the formation of hydrogen bonds.
