Recently, many high-throughput calculation materials databases have been constructed and found wide applications. However, a database is only useful if its content is reliable and sufficiently accurate. It is thus of ...Recently, many high-throughput calculation materials databases have been constructed and found wide applications. However, a database is only useful if its content is reliable and sufficiently accurate. It is thus of paramount importance to gauge the reliabilities and accuracies of these databases. Although many properties have been predicted accurately in these databases,electronic band gap is well known to be underestimated by traditional density functional theory(DFT) calculations under local density approximation(LDA), which becomes a challenging problem for materials database building. Here, we introduce MaterialGo(http://www.pkusam.com/data-base.html), a new database calculating the band structures of crystals using both Perdew-Burke-Ernzerhof(PBE) exchange-correlation functional and Heyd-Scuseria-Ernzerhof(HSE) hybrid functional.Comparing different PBE databases, it is found that their band gaps are consistent when no U parameter is used for transition metal d-state or heavy element f-state to correct their self-interaction error, but rather different when PBE+U are used, mostly because of the different values of U used in different database. HSE calculations under standard parameters will give larger band gaps that are closer to experiment. Based on the high-throughput HSE calculations over 10000 crystal structures, we might have a better understanding of the relationship between crystal structures and electronic structures, which will help us to further explore material genome science and engineering.展开更多
Hybrid density functional theory is employed to systematically investigate the structural,magnetic,vibrational,thermodynamic properties of plutonium monocarbide（Pu C and Pu C0.75）.For comparison,the results obtained...Hybrid density functional theory is employed to systematically investigate the structural,magnetic,vibrational,thermodynamic properties of plutonium monocarbide（Pu C and Pu C0.75）.For comparison,the results obtained by DFT,DFT ＋ U are also given.For Pu C and Pu C0.75,Fock-0.25 hybrid functional gives the best lattice constants and predicts the correct ground states of antiferromagnetic（AFM） structure.The calculated phonon spectra suggest that Pu C and Pu C0.75 are dynamically stable.Values of the Helmholtz free energy ？F,internal energy ？E,entropy S,and constant-volume specific heat Cv of Pu C and Pu C0.75 are given.The results are in good agreement with available experimental or theoretical data.As for the chemical bonding nature,the difference charge densities,the partial densities of states and the Bader charge analysis suggest that the Pu–C bonds of Pu C and Pu C0.75 have a mixture of covalent character and ionic character.The effect of carbon vacancy on the chemical bonding is also discussed in detail.We expect that our study can provide some useful reference for further experimental research on the phonon density of states,thermodynamic properties of the plutonium monocarbide.展开更多
Structural, electronic and optical properties of Sc-based aluminum-nitride alloy have been carried out with first-principles methods using both local density approximation (LDA) and Heyd-Scuseria-Ernzerhof (HSE) hybri...Structural, electronic and optical properties of Sc-based aluminum-nitride alloy have been carried out with first-principles methods using both local density approximation (LDA) and Heyd-Scuseria-Ernzerhof (HSE) hybrid functional. This latter provides a more accurate description of the lattice parameters, enthalpy of formation, electronic and optical properties of our alloy than standard DFT. We found the transition from wurtzite to rocksalt structures at 61% of Sc concentration. By increasing the scandium concentration, the lattice parameters and the band gap decrease. The HSE band gap is in good agreement with available experimental data. The existence of the strong hybridization between Sc 3d and N 2p indicates the transport of electrons from Sc to N atoms. Besides, it is shown that the insertion of the Sc atom leads to the redshift of the optical absorption edge. The optical absorption of Sc<sub>x</sub>Al<sub>1-x</sub>N is found to decrease with increasing Sc concentrations in the low energy range. Because of this, Sc<sub>x</sub>Al<sub>1-x</sub>N have a great potential for applications in photovoltaics and photocatalysis.展开更多
We apply the Heyd-Scuseria-Ernzerhof hybrid functional calculation to study the（2, 3） nanotube codoped with various compositions of nitrogen and boron atoms. We find that the bandgaps and other properties of doped n...We apply the Heyd-Scuseria-Ernzerhof hybrid functional calculation to study the（2, 3） nanotube codoped with various compositions of nitrogen and boron atoms. We find that the bandgaps and other properties of doped nanotubes oscillate with the doped compositions. Our study should shed light on the understanding of the properties of doped small nanotubes. This might have potential in designing new nano electronic-devices.展开更多
The electronic properties of zinc-blende BxGal-xN alloys are comparatively investigated by employ- ing both the Perdewe-Burkee-Ernzerhof generalized-gradient approximation （PBE-GGA） and the Heyd-Scuseria- Ernzerhof ...The electronic properties of zinc-blende BxGal-xN alloys are comparatively investigated by employ- ing both the Perdewe-Burkee-Ernzerhof generalized-gradient approximation （PBE-GGA） and the Heyd-Scuseria- Ernzerhof screened hybrid functional methods （HSE06）. HSE06 reproduced much closer ground-state properties to experiments. Large and composition-dependent bowing parameters br for the direct band gaps were obtained from both PBE and HSE06. The crossover composition where alloy switches from direct to indirect was predicted to occur at very similar x from PBE and HSE06. We can obtain direct gap BxGal-xN with a gap value much larger than that of GaN by alloying x 〈 0.557 boron into GaN.展开更多
Point mutations on membrane proteins may lead to small structural variations. Prediction of such struc- tural variations can help to further understand the related bio-activities of membrane proteins. We constructed f...Point mutations on membrane proteins may lead to small structural variations. Prediction of such struc- tural variations can help to further understand the related bio-activities of membrane proteins. We constructed fifteen hybrid energy functions on the basis of Chemistry at Harvard Macromolecular Mechanics（CHARMM） force field, hydrogen bonding potential and distance-scaled, finite ideal-gas reference（DFIRE）-like statistical energies, and eva- luated their performance on a representative dataset of homologous membrane proteins via a newly developed all-atom replica exchange Monte Carlo algorithm. The energy function composed of CHARMM and hydrogen bonding potential has the best performance, and the original DFIRE potential shows much better performance than the DFIRE-Iike potentials constructed from membrane proteins. We can conclude that more membrane protein struc- tures with high resolution are necessary for the construction of robust prediction method of mutation induced mem- brane protein structure variations.展开更多
基金supported by the National Key R&D Program of China(Grant No.2016YFB0700600)the Shenzhen Science and Technology Research Grant(Grant No.ZDSYS201707281026184)+1 种基金the Guangdong Key-lab Project(Grant No.2017B0303010130)Wang is supported by the Director Office of Science(SC)、Basic Energy Science(BES)、Materials Science and Engineering Division (MSED) of the US Department of Energy(DOE)under Contract No.DE-AC02-05CH11231 through the Materials Theory program(KC2301)
文摘Recently, many high-throughput calculation materials databases have been constructed and found wide applications. However, a database is only useful if its content is reliable and sufficiently accurate. It is thus of paramount importance to gauge the reliabilities and accuracies of these databases. Although many properties have been predicted accurately in these databases,electronic band gap is well known to be underestimated by traditional density functional theory(DFT) calculations under local density approximation(LDA), which becomes a challenging problem for materials database building. Here, we introduce MaterialGo(http://www.pkusam.com/data-base.html), a new database calculating the band structures of crystals using both Perdew-Burke-Ernzerhof(PBE) exchange-correlation functional and Heyd-Scuseria-Ernzerhof(HSE) hybrid functional.Comparing different PBE databases, it is found that their band gaps are consistent when no U parameter is used for transition metal d-state or heavy element f-state to correct their self-interaction error, but rather different when PBE+U are used, mostly because of the different values of U used in different database. HSE calculations under standard parameters will give larger band gaps that are closer to experiment. Based on the high-throughput HSE calculations over 10000 crystal structures, we might have a better understanding of the relationship between crystal structures and electronic structures, which will help us to further explore material genome science and engineering.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.21371160 and 21401173)
文摘Hybrid density functional theory is employed to systematically investigate the structural,magnetic,vibrational,thermodynamic properties of plutonium monocarbide（Pu C and Pu C0.75）.For comparison,the results obtained by DFT,DFT ＋ U are also given.For Pu C and Pu C0.75,Fock-0.25 hybrid functional gives the best lattice constants and predicts the correct ground states of antiferromagnetic（AFM） structure.The calculated phonon spectra suggest that Pu C and Pu C0.75 are dynamically stable.Values of the Helmholtz free energy ？F,internal energy ？E,entropy S,and constant-volume specific heat Cv of Pu C and Pu C0.75 are given.The results are in good agreement with available experimental or theoretical data.As for the chemical bonding nature,the difference charge densities,the partial densities of states and the Bader charge analysis suggest that the Pu–C bonds of Pu C and Pu C0.75 have a mixture of covalent character and ionic character.The effect of carbon vacancy on the chemical bonding is also discussed in detail.We expect that our study can provide some useful reference for further experimental research on the phonon density of states,thermodynamic properties of the plutonium monocarbide.
基金Supported by State Key Program for Basic Research of China(2013 CB632705,2011 CB922004)National Natural Science Foundation of China(11334008,61290301)Fund of Shanghai Science and Technology Foundation(13 JC1408800)
文摘Structural, electronic and optical properties of Sc-based aluminum-nitride alloy have been carried out with first-principles methods using both local density approximation (LDA) and Heyd-Scuseria-Ernzerhof (HSE) hybrid functional. This latter provides a more accurate description of the lattice parameters, enthalpy of formation, electronic and optical properties of our alloy than standard DFT. We found the transition from wurtzite to rocksalt structures at 61% of Sc concentration. By increasing the scandium concentration, the lattice parameters and the band gap decrease. The HSE band gap is in good agreement with available experimental data. The existence of the strong hybridization between Sc 3d and N 2p indicates the transport of electrons from Sc to N atoms. Besides, it is shown that the insertion of the Sc atom leads to the redshift of the optical absorption edge. The optical absorption of Sc<sub>x</sub>Al<sub>1-x</sub>N is found to decrease with increasing Sc concentrations in the low energy range. Because of this, Sc<sub>x</sub>Al<sub>1-x</sub>N have a great potential for applications in photovoltaics and photocatalysis.
文摘We apply the Heyd-Scuseria-Ernzerhof hybrid functional calculation to study the（2, 3） nanotube codoped with various compositions of nitrogen and boron atoms. We find that the bandgaps and other properties of doped nanotubes oscillate with the doped compositions. Our study should shed light on the understanding of the properties of doped small nanotubes. This might have potential in designing new nano electronic-devices.
基金supported by the Fundamental Research Funds for the Central Universities(No.2010LKWL03)the Special Fund for Theoretical Physics(No.11047130)the National Natural Science Foundation of China(No.11104345)
文摘The electronic properties of zinc-blende BxGal-xN alloys are comparatively investigated by employ- ing both the Perdewe-Burkee-Ernzerhof generalized-gradient approximation （PBE-GGA） and the Heyd-Scuseria- Ernzerhof screened hybrid functional methods （HSE06）. HSE06 reproduced much closer ground-state properties to experiments. Large and composition-dependent bowing parameters br for the direct band gaps were obtained from both PBE and HSE06. The crossover composition where alloy switches from direct to indirect was predicted to occur at very similar x from PBE and HSE06. We can obtain direct gap BxGal-xN with a gap value much larger than that of GaN by alloying x 〈 0.557 boron into GaN.
文摘Point mutations on membrane proteins may lead to small structural variations. Prediction of such struc- tural variations can help to further understand the related bio-activities of membrane proteins. We constructed fifteen hybrid energy functions on the basis of Chemistry at Harvard Macromolecular Mechanics（CHARMM） force field, hydrogen bonding potential and distance-scaled, finite ideal-gas reference（DFIRE）-like statistical energies, and eva- luated their performance on a representative dataset of homologous membrane proteins via a newly developed all-atom replica exchange Monte Carlo algorithm. The energy function composed of CHARMM and hydrogen bonding potential has the best performance, and the original DFIRE potential shows much better performance than the DFIRE-Iike potentials constructed from membrane proteins. We can conclude that more membrane protein struc- tures with high resolution are necessary for the construction of robust prediction method of mutation induced mem- brane protein structure variations.
