In this work it is shown that the kinetic energy and the exchange-correlation energy are mutual dependent on each other.This aspect is first derived in an orbital-free context.It is shown that the total Fermi potentia...In this work it is shown that the kinetic energy and the exchange-correlation energy are mutual dependent on each other.This aspect is first derived in an orbital-free context.It is shown that the total Fermi potential depends on the density only,the individual parts,the Pauli kinetic energy and the exchange-correlation energy,however,are orbital dependent and as such mutually influence each other.The numerical investigation is performed for the orbital-based non-interacting Kohn-Sham system in order to avoid additional effects due to further approximations of the kinetic energy.The numerical influence of the exchange-correlation functional on the non-interacting kinetic energy is shown to be of the orderof a few Hartrees.For chemical purposes,however,the energetic performance as a function of the nuclear coordinates is much more important than total energies.Therefore,the effect on the bond dissociation curve was studied exemplarily for the carbon monoxide.The data reveals that,the mutual influence between the exchange-correlation functional and the kinetic energy has a significant influence on bond dissociation energies and bond distances.Therefore,the effect of the exchange-correlation treatment must be considered in the design of orbital-free density functional approximations for the kinetic energy.展开更多
Density functional theory(DFT)has been established as a powerful research tool for heterogeneous catalysis research in obtaining key thermodynamic and/or kinetic parameters like adsorption energies,enthalpies of react...Density functional theory(DFT)has been established as a powerful research tool for heterogeneous catalysis research in obtaining key thermodynamic and/or kinetic parameters like adsorption energies,enthalpies of reaction,activation barriers,and rate constants.Understanding of density functional exchangecorrelation approximations is essential to reveal the mechanism and performance of a catalyst.In the present work,we reported the influence of six exchange-correlation density functionals,including PBE,RPBE,BEEF+vdW,optB86b+vdW,SCAN,and SCAN+rVV10,on the adsorption energies,reaction energies and activation barriers of carbon hydrogenation and carbon-carbon couplings during the formation of methane and ethane over Ru(0001)and Ru(1011)surfaces.We found the calculated reaction energies are strongly dependent on exchange-correlation density functionals due to the difference in coordination number between reactants and products on surfaces.The deviation of the calculated elementary reaction energies can be accumulated to a large value for chemical reaction involving multiple steps and vary considerably with different exchange-correlation density functionals calculations.The different exchange-correlation density functionals are found to influence considerably the selectivity of Ru(0001)surface for methane,ethylene,and ethane formation determined by the adsorption energies of intermediates involved.However,the influence on the barriers of the elementary surface reactions and the structural sensitivity of Ru(0001)and Ru(1011)are modest.Our work highlights the limitation of exchange-correlation density functionals on computational catalysis and the importance of choosing a proper exchange-correlation density functional in correctly evaluating the activity and selectivity of a catalyst.展开更多
We examine the effect of the electron exchange-correlation on weak and arbitrary amplitude quantum dust ion-acoustic(QDIA) solitons.The reduced quantum hydrodynamic(QHD) model is used.Carrying out a fully nonlinear an...We examine the effect of the electron exchange-correlation on weak and arbitrary amplitude quantum dust ion-acoustic(QDIA) solitons.The reduced quantum hydrodynamic(QHD) model is used.Carrying out a fully nonlinear analysis,it is found that the effect of the exchange-correlation on the main quantities for solitary-wave propagation can be quite important.In particular,it may be noted that the arbitrary amplitude QDIA soliton experiences a spreading as the phenomenon of exchange-correlation becomes effective.Furthermore,our results show that the exchange-correlation effects inhibit the formation of the flat-bottomed solitons and do not favor their emergence.It turns out that exchangecorrelation and quantum diffraction may act concurrently to set up the conditions for the existence of the QDIA solitary waves.Our results complement and provide new insight into our previously published work on this problem.展开更多
Parametric instabilities induced by the nonlinear interaction between high frequency quantum Langmuir waves and low frequency quantum ion-acoustic waves in quantum plasmas with the electron exchange-correlation effect...Parametric instabilities induced by the nonlinear interaction between high frequency quantum Langmuir waves and low frequency quantum ion-acoustic waves in quantum plasmas with the electron exchange-correlation effects are presented.By using the quantum hydrodynamic equations with the electron exchange-correlation correction,we obtain an effective quantum Zaharov model,which is then used to derive the modified dispersion relations and the growth rates of the decay and four-wave instabilities.The influences of the electron exchange-correlation effects and the quantum effects on the existence of quantum Langmuir waves and the parametric instabilities are discussed in detail.It is shown that the electron exchange-correlation effects and quantum effects are strongly coupled.The quantum Langmuir wave can propagate in quantum plasmas only when the electron exchange-correlation effects and the quantum effects satisfy a certain condition.The electron exchange-correlation effects tend to enhance the parametric instabilities,while quantum effects suppress the instabilities.展开更多
Calculation of total energies of the electronic ground states of atoms forms the basis for the frozen-core pseudopotentials used in atomistic calculations of much larger scale. Reference values for these energies prov...Calculation of total energies of the electronic ground states of atoms forms the basis for the frozen-core pseudopotentials used in atomistic calculations of much larger scale. Reference values for these energies provide a benchmark for the validation of new software to calculate such potentials. In addition, basic atomic-scale electronic properties such as the (first) ionization energy provide a simple check on the approximation used in the calculation method. We present a comparison of the total energies and ionization energies of atoms Z = 1 - 92 calculated in density functional theory with several levels of exchange-correlation functional and the Hartree-Fock method, comparing ionization energies to experiment. We also investigate the role of relativistic treatment on these energies.展开更多
By solving the total energy equation, we obtain the formula of exchange-correlation functional for the first time. This functional is usually determined by fitting experimental data or the numerical results of models....By solving the total energy equation, we obtain the formula of exchange-correlation functional for the first time. This functional is usually determined by fitting experimental data or the numerical results of models. In the uniform electron gas limit, our exchangecorrelation functional can exactly reproduce the results of Perdew-Zunger parameterization from the jellium model. By making use of a particular solution, our exchange-correlation functional could take into accotmt the case of non-uniform electron density, and its validity can be confirmed through comparisons of the band structure, equilibrium lattice constant, and bulk modulus of aluminum and silicon. The absence of mechanical prescriptions for the systematic improvement of exchange-correlation functional hinders further development of density-functional theory （DFT）, and the formula of exchange-correlation functional given in this study might provide a new perspective to help DFT out of this awkward situation.展开更多
Machine learning(ML)has demon-strated significant potential in en-hancing the predictive capabilities of density functional theory methods.In this study,we develop an ML model for correcting B3LYP-D,a density function...Machine learning(ML)has demon-strated significant potential in en-hancing the predictive capabilities of density functional theory methods.In this study,we develop an ML model for correcting B3LYP-D,a density functional approximation that incorporates dispersion correc-tions for non-covalent interactions.This model utilizes semilocal elec-tron density descriptors,and is trained with accurate reference data for both relative and ab-solute energies.Extensive benchmark tests reveal that the ML correction substantially en-hances the generalization ability of the B3LYP-D functional,improving the predictions of at-omization and dissociation energies for complex molecular systems.It retains the accuracy of B3LYP-D in predicting reaction barrier heights and non-covalent interactions while enabling efficient,fully self-consistent field calculations.This work signifies a promising advancement in the development of ML-corrected functionals that surpass the performance of traditional B3LYP-D.展开更多
Accurate description of the adsorption process of reactants on metal surfaces from theory is crucial for mechanistic understanding of activity and selectivity of metal catalysts, but it remains challengeable for the n...Accurate description of the adsorption process of reactants on metal surfaces from theory is crucial for mechanistic understanding of activity and selectivity of metal catalysts, but it remains challengeable for the nowadays first-principles theory due to the lack of proper exchange-correlation functional describing the distinct interactions involved. We studied here the potential energy surfaces of ethylene adsorption on Ag(111), Rh(111) and Ir(111) using density functional theory calculations and (meta)-GGA functional including PBE, BEEF-vdW, SCAN, and SCAN+rVV10. For ethylene adsorption on noble metal Ag(111), it is found that BEEF-vdW, SCAN and SCAN+rVV10 predict the presence of the physisorption states only. For Rh(111), both SCAN and SCAN+rVV10 find that there is a precursor physisorption state before the chemisorption state. In contrast, there is no precursor state found based on potential energy surfaces from BEEF-vdW and PBE. Whereas for Ir(111), BEEF-vdW predicts the existence of a rather shallow precursor physisorption state, in addition to the chemisorption state. Irrespective to the transition metals considered, we find that SCAN+rVV10 gives the strongest binding strength, followed by SCAN, and PBE/BEEF-vdW, accordingly. The present work highlights great dependence of potential energy surface of ethylene adsorption on transition metal surfaces and exchange-correlation functionals.展开更多
This paper presents calculating results of the two-dimensional electron gas （2DEG） distributions in AlGaN/GaN material system by solving the Schroedinger and Poisson equations self-consistently. Due to high 2DEG den...This paper presents calculating results of the two-dimensional electron gas （2DEG） distributions in AlGaN/GaN material system by solving the Schroedinger and Poisson equations self-consistently. Due to high 2DEG density in the AlGaN/GaN heterojunction interface, the exchange correlation potential should be considered among the potential energy item of Schroedinger equation. Analysis of the exchange correlation potential is given. The dependencies of the conduction band edge, 2DEG density on the Al mole fraction are presented. The polarization fields have strong influence on 2DEG density in the AlGaN/GaN heterojunction, so the dependency of the conduction band edge on the polarization is also given.展开更多
A spin-dependent quantum trajectory methodology is outlined which achieves electron exchangecorrelation on an ab initio basis. The methodology is intended to give workers in electronic structure the same computational...A spin-dependent quantum trajectory methodology is outlined which achieves electron exchangecorrelation on an ab initio basis. The methodology is intended to give workers in electronic structure the same computational capability which has been available for decades in classical dynamics.展开更多
We introduce a formal definition of a non local functional and show that the non local exchange-correlation potential functional, derived within Density-Functional Theory, is non local in the space of electronic densi...We introduce a formal definition of a non local functional and show that the non local exchange-correlation potential functional, derived within Density-Functional Theory, is non local in the space of electronic densities. A previously developed non local exchange-correlation potential term, is introduced to approach the exact density-functional potential. With this approach, the electronic structure of the graphene surface and the tyrosine amino acid are calculated.展开更多
基金The project was supported by the Fund for Scientific Research in Flanders (FWO-Vlaanderen) for Research Grant G021115N.
文摘In this work it is shown that the kinetic energy and the exchange-correlation energy are mutual dependent on each other.This aspect is first derived in an orbital-free context.It is shown that the total Fermi potential depends on the density only,the individual parts,the Pauli kinetic energy and the exchange-correlation energy,however,are orbital dependent and as such mutually influence each other.The numerical investigation is performed for the orbital-based non-interacting Kohn-Sham system in order to avoid additional effects due to further approximations of the kinetic energy.The numerical influence of the exchange-correlation functional on the non-interacting kinetic energy is shown to be of the orderof a few Hartrees.For chemical purposes,however,the energetic performance as a function of the nuclear coordinates is much more important than total energies.Therefore,the effect on the bond dissociation curve was studied exemplarily for the carbon monoxide.The data reveals that,the mutual influence between the exchange-correlation functional and the kinetic energy has a significant influence on bond dissociation energies and bond distances.Therefore,the effect of the exchange-correlation treatment must be considered in the design of orbital-free density functional approximations for the kinetic energy.
基金This work was supported by the Key Technologies R&D Program of China(No.2018YFA0208603)the National Natural Science Foundation of China(No.22172150 and No.91945302)+5 种基金the Chinese Academy of Sciences Key Project(QYZDJ-SSW-SLH054)the Start-up Funds of University of Science and Technology of China(No.KY2060000171)the National Natural Science Foundation of Anhui province(No.2108085QB62)USTC Research Funds of the Double First-Class Initiative(No.YD2060002012)K.C.Wong Education(No.GJTD-2020-15)highPerformance Computational Resources provided by the University of Science and Technology of China(http://scc.ustc.edu.cn)and Hefei Advanced Computing center.
文摘Density functional theory(DFT)has been established as a powerful research tool for heterogeneous catalysis research in obtaining key thermodynamic and/or kinetic parameters like adsorption energies,enthalpies of reaction,activation barriers,and rate constants.Understanding of density functional exchangecorrelation approximations is essential to reveal the mechanism and performance of a catalyst.In the present work,we reported the influence of six exchange-correlation density functionals,including PBE,RPBE,BEEF+vdW,optB86b+vdW,SCAN,and SCAN+rVV10,on the adsorption energies,reaction energies and activation barriers of carbon hydrogenation and carbon-carbon couplings during the formation of methane and ethane over Ru(0001)and Ru(1011)surfaces.We found the calculated reaction energies are strongly dependent on exchange-correlation density functionals due to the difference in coordination number between reactants and products on surfaces.The deviation of the calculated elementary reaction energies can be accumulated to a large value for chemical reaction involving multiple steps and vary considerably with different exchange-correlation density functionals calculations.The different exchange-correlation density functionals are found to influence considerably the selectivity of Ru(0001)surface for methane,ethylene,and ethane formation determined by the adsorption energies of intermediates involved.However,the influence on the barriers of the elementary surface reactions and the structural sensitivity of Ru(0001)and Ru(1011)are modest.Our work highlights the limitation of exchange-correlation density functionals on computational catalysis and the importance of choosing a proper exchange-correlation density functional in correctly evaluating the activity and selectivity of a catalyst.
文摘We examine the effect of the electron exchange-correlation on weak and arbitrary amplitude quantum dust ion-acoustic(QDIA) solitons.The reduced quantum hydrodynamic(QHD) model is used.Carrying out a fully nonlinear analysis,it is found that the effect of the exchange-correlation on the main quantities for solitary-wave propagation can be quite important.In particular,it may be noted that the arbitrary amplitude QDIA soliton experiences a spreading as the phenomenon of exchange-correlation becomes effective.Furthermore,our results show that the exchange-correlation effects inhibit the formation of the flat-bottomed solitons and do not favor their emergence.It turns out that exchangecorrelation and quantum diffraction may act concurrently to set up the conditions for the existence of the QDIA solitary waves.Our results complement and provide new insight into our previously published work on this problem.
基金Project supported by the National Natural Science Foundation of China (Grant No. 10975114)the Foundation for the Creation of Science and Technology of the Northwest Normal University of China (Grant No. NWNU-KJCXGC-03-48)
文摘Parametric instabilities induced by the nonlinear interaction between high frequency quantum Langmuir waves and low frequency quantum ion-acoustic waves in quantum plasmas with the electron exchange-correlation effects are presented.By using the quantum hydrodynamic equations with the electron exchange-correlation correction,we obtain an effective quantum Zaharov model,which is then used to derive the modified dispersion relations and the growth rates of the decay and four-wave instabilities.The influences of the electron exchange-correlation effects and the quantum effects on the existence of quantum Langmuir waves and the parametric instabilities are discussed in detail.It is shown that the electron exchange-correlation effects and quantum effects are strongly coupled.The quantum Langmuir wave can propagate in quantum plasmas only when the electron exchange-correlation effects and the quantum effects satisfy a certain condition.The electron exchange-correlation effects tend to enhance the parametric instabilities,while quantum effects suppress the instabilities.
文摘Calculation of total energies of the electronic ground states of atoms forms the basis for the frozen-core pseudopotentials used in atomistic calculations of much larger scale. Reference values for these energies provide a benchmark for the validation of new software to calculate such potentials. In addition, basic atomic-scale electronic properties such as the (first) ionization energy provide a simple check on the approximation used in the calculation method. We present a comparison of the total energies and ionization energies of atoms Z = 1 - 92 calculated in density functional theory with several levels of exchange-correlation functional and the Hartree-Fock method, comparing ionization energies to experiment. We also investigate the role of relativistic treatment on these energies.
基金supported by the National High Technology Research and Development Program of China(Grants Nos.2014CB920903 and 2011CBA00100)the National Natural Science Foundation of China(Grant Nos.11021262,107212303,10372107,11174337 and 11225418)+1 种基金the National Basic Research Program of China(Grants No.2012CB937500)the Specialized Research Fund for the Doctoral Program of Higher Education of China(Grants No.20121101110046)
文摘By solving the total energy equation, we obtain the formula of exchange-correlation functional for the first time. This functional is usually determined by fitting experimental data or the numerical results of models. In the uniform electron gas limit, our exchangecorrelation functional can exactly reproduce the results of Perdew-Zunger parameterization from the jellium model. By making use of a particular solution, our exchange-correlation functional could take into accotmt the case of non-uniform electron density, and its validity can be confirmed through comparisons of the band structure, equilibrium lattice constant, and bulk modulus of aluminum and silicon. The absence of mechanical prescriptions for the systematic improvement of exchange-correlation functional hinders further development of density-functional theory （DFT）, and the formula of exchange-correlation functional given in this study might provide a new perspective to help DFT out of this awkward situation.
基金supported by the National Natural Science Foundation of China(Nos.22393912,22425301,22373091,22173088)the AI for Science Foundation of Fudan University(No.Fudan X24AI023)the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB0450101).
文摘Machine learning(ML)has demon-strated significant potential in en-hancing the predictive capabilities of density functional theory methods.In this study,we develop an ML model for correcting B3LYP-D,a density functional approximation that incorporates dispersion correc-tions for non-covalent interactions.This model utilizes semilocal elec-tron density descriptors,and is trained with accurate reference data for both relative and ab-solute energies.Extensive benchmark tests reveal that the ML correction substantially en-hances the generalization ability of the B3LYP-D functional,improving the predictions of at-omization and dissociation energies for complex molecular systems.It retains the accuracy of B3LYP-D in predicting reaction barrier heights and non-covalent interactions while enabling efficient,fully self-consistent field calculations.This work signifies a promising advancement in the development of ML-corrected functionals that surpass the performance of traditional B3LYP-D.
基金supported by the National Key R&D Program of China (No.2017YFB0602205 and No.2018YFA0208603)the National Natural Science Foundation of China (No.91645202)the Chinese Academy of Sciences (No.QYZDJ-SSW-SLH054)
文摘Accurate description of the adsorption process of reactants on metal surfaces from theory is crucial for mechanistic understanding of activity and selectivity of metal catalysts, but it remains challengeable for the nowadays first-principles theory due to the lack of proper exchange-correlation functional describing the distinct interactions involved. We studied here the potential energy surfaces of ethylene adsorption on Ag(111), Rh(111) and Ir(111) using density functional theory calculations and (meta)-GGA functional including PBE, BEEF-vdW, SCAN, and SCAN+rVV10. For ethylene adsorption on noble metal Ag(111), it is found that BEEF-vdW, SCAN and SCAN+rVV10 predict the presence of the physisorption states only. For Rh(111), both SCAN and SCAN+rVV10 find that there is a precursor physisorption state before the chemisorption state. In contrast, there is no precursor state found based on potential energy surfaces from BEEF-vdW and PBE. Whereas for Ir(111), BEEF-vdW predicts the existence of a rather shallow precursor physisorption state, in addition to the chemisorption state. Irrespective to the transition metals considered, we find that SCAN+rVV10 gives the strongest binding strength, followed by SCAN, and PBE/BEEF-vdW, accordingly. The present work highlights great dependence of potential energy surface of ethylene adsorption on transition metal surfaces and exchange-correlation functionals.
基金Project supported by the Foundation of Hebei Education Department, China (Grant No 2003130)
文摘This paper presents calculating results of the two-dimensional electron gas （2DEG） distributions in AlGaN/GaN material system by solving the Schroedinger and Poisson equations self-consistently. Due to high 2DEG density in the AlGaN/GaN heterojunction interface, the exchange correlation potential should be considered among the potential energy item of Schroedinger equation. Analysis of the exchange correlation potential is given. The dependencies of the conduction band edge, 2DEG density on the Al mole fraction are presented. The polarization fields have strong influence on 2DEG density in the AlGaN/GaN heterojunction, so the dependency of the conduction band edge on the polarization is also given.
文摘A spin-dependent quantum trajectory methodology is outlined which achieves electron exchangecorrelation on an ab initio basis. The methodology is intended to give workers in electronic structure the same computational capability which has been available for decades in classical dynamics.
文摘We introduce a formal definition of a non local functional and show that the non local exchange-correlation potential functional, derived within Density-Functional Theory, is non local in the space of electronic densities. A previously developed non local exchange-correlation potential term, is introduced to approach the exact density-functional potential. With this approach, the electronic structure of the graphene surface and the tyrosine amino acid are calculated.
