Based on the density functional theory,we described here a method to investigate the quantitative relationship between nucleophilicity/basicity and HSAB-theory-based properties of compounds with lone-pair electrons.De...Based on the density functional theory,we described here a method to investigate the quantitative relationship between nucleophilicity/basicity and HSAB-theory-based properties of compounds with lone-pair electrons.Descriptors including global softness,Fukui function,local softness and local mulliken charge were calculated at SVWN/DN~* level of DFT with PC Spartan Pro.Nucleophilicity and basicity of 28 selected compounds were classified based on intensity.BP algorithm of artificial neural network(ANN) was employed to study the relationship between the descriptors and nucleophilicity/basicity.Cross-validation was carried out to avoid the over-fitting in training of ANN.A BP network was trained to quantify the relationship between HSAB-theory-based properties and nucleophilicity/basicity of compounds with lone-pair electrons.The results show that the prediction based on the network matches with the experimental results well.The local softness and Fukui function have a better relationship with nucleophilicity and local mulliken charge than with the basicity.The trained BP network could be utilized for predicting the nucleophilicity/basicity of compounds or functional groups with lone-pair electrons.展开更多
Based on the density functional theory, we described here a method to investigate the quantitative relationship between nucleophilicity/basicity and HSAB-theory-based properties of compounds with lone-pair electrons. ...Based on the density functional theory, we described here a method to investigate the quantitative relationship between nucleophilicity/basicity and HSAB-theory-based properties of compounds with lone-pair electrons. Descriptors including global softness, Fukui function, local softness and local mulliken charge were calculated at SVWN/DN＊ level of DFT with PC Spartan Pro. Nucleophilicity and basicity of 28 selected compounds were classified based on intensity. BP algorithm of artificial neural network （ANN） was employed to study the relationship between the descriptors and nucleophilicity/basicity. Cross-validation was carried out to avoid the over-fitting in training of ANN. A BP network was trained to quantify the relationship between HSAB-theory-based properties and nucleophilicity/basicity of compounds with lone-pair electrons. The results show that the prediction based on the network matches with the experimental results well. The local softness and Fukui function have a better relationship with nucleophilicity and local mulliken charge than with the basicity. The trained BP network could be utilized for predicting the nucleophilicity/basicity of compounds or functional groups with lone-pair electrons.展开更多
Designing novel van der Waals layered materials with low thermal conductivity and large power factor is important for the development of layered thermoelectric materials.Therefore,the novel van der Waals intercalated ...Designing novel van der Waals layered materials with low thermal conductivity and large power factor is important for the development of layered thermoelectric materials.Therefore,the novel van der Waals intercalated compound La_(2)Bi_(4)Cu_(2)O_(6)Se_(4),which is constructed by alternately stacking LaCuSeO and Bi_(2)O_(2)Se units along the c-axis in a 1:2 ratio,has designed for thermoelectric materials.The unique intercalated strategy leads to the four-band convergence at the valence band maximum,and the combination of multiple heavy band and light band,which significantly enhances the p-type doping power factor.The lattice thermal conductivities in La_(2)Bi_(4)Cu_(2)O_(6)Se_(4)and LaCuSeO compounds are accurately calculated by considering the coherence contributions of the anharmonic phonon reformulations and the off-diagonal term of the heat flux operator.The weak bond property of the Cu d-Se p bonding causes phonon softening,reducing the lattice thermal conductivity.The intercalated Bi atom has stereochemically active lone-pair electrons,which causes acoustic-optical coupling and produces strong fourth acoustic-optical phonon scattering,suppressing low-frequency phonon transport.The carrier relaxation time is rationalized by considering multiple carrier scattering mechanisms.The p-type doping La_(2)Bi_(4)Cu_(2)O_(6)Se_(4)achieves an average ZT of 2.3 at 700 K,and an optimal ZT of 2.7 along the in-plane direction.Our current work not only reveals the origin of the strong phonon scattering and large power factor of La_(2)Bi_(4)Cu_(2)O_(6)Se_(4)compound,but also provides theoretical guidance for the design of La-based layered oxides for thermoelectric applications.展开更多
Here an electron momentum spectroscopy study on the electronic structure of valence shell of iso-dichloroethylene molecule is reported. The experiment is carried out with a binary (e, 2e) spectrometer at incident elec...Here an electron momentum spectroscopy study on the electronic structure of valence shell of iso-dichloroethylene molecule is reported. The experiment is carried out with a binary (e, 2e) spectrometer at incident electron energy of 1200 eV, employing noncoplanar symmetric arrangement. The binding energy spectra and electron momentum distributions (EMDs) of iso-dichloroethylene valence shell have been obtained. Theoretical EMDs are predicted with both Hartree-Fock and density functional theory methods, generally indicating good agreements with the measurement results. The interference effect is observed to significantly influence the EMDs of 2a2 and 5b2 Cl lone-pair orbitals.展开更多
基金National Science & Technology Major Project of China(Grant No.2009ZX09501-002)National Natural Science Foundation of China(Grant No.20802006).
文摘Based on the density functional theory,we described here a method to investigate the quantitative relationship between nucleophilicity/basicity and HSAB-theory-based properties of compounds with lone-pair electrons.Descriptors including global softness,Fukui function,local softness and local mulliken charge were calculated at SVWN/DN~* level of DFT with PC Spartan Pro.Nucleophilicity and basicity of 28 selected compounds were classified based on intensity.BP algorithm of artificial neural network(ANN) was employed to study the relationship between the descriptors and nucleophilicity/basicity.Cross-validation was carried out to avoid the over-fitting in training of ANN.A BP network was trained to quantify the relationship between HSAB-theory-based properties and nucleophilicity/basicity of compounds with lone-pair electrons.The results show that the prediction based on the network matches with the experimental results well.The local softness and Fukui function have a better relationship with nucleophilicity and local mulliken charge than with the basicity.The trained BP network could be utilized for predicting the nucleophilicity/basicity of compounds or functional groups with lone-pair electrons.
基金Foundation items： National Science ＆ Technology Major Project of China （Grant No. 2009ZX09501-002）, National Natural Science Foundation of China （Grant No. 20802006）.
文摘Based on the density functional theory, we described here a method to investigate the quantitative relationship between nucleophilicity/basicity and HSAB-theory-based properties of compounds with lone-pair electrons. Descriptors including global softness, Fukui function, local softness and local mulliken charge were calculated at SVWN/DN＊ level of DFT with PC Spartan Pro. Nucleophilicity and basicity of 28 selected compounds were classified based on intensity. BP algorithm of artificial neural network （ANN） was employed to study the relationship between the descriptors and nucleophilicity/basicity. Cross-validation was carried out to avoid the over-fitting in training of ANN. A BP network was trained to quantify the relationship between HSAB-theory-based properties and nucleophilicity/basicity of compounds with lone-pair electrons. The results show that the prediction based on the network matches with the experimental results well. The local softness and Fukui function have a better relationship with nucleophilicity and local mulliken charge than with the basicity. The trained BP network could be utilized for predicting the nucleophilicity/basicity of compounds or functional groups with lone-pair electrons.
基金Financial supports from the National Natural Science Foundation of China(Grant No.21503039)Department of Science and Technology of Liaoning Province(Grant No.2019MS164)+1 种基金Department of Education of Liaoning Province(Grant No.LJ2020JCL034)Discipline Innovation Team of Liaoning Technical University(Grant No.LNTU20TD-16)are greatly acknowledged。
文摘Designing novel van der Waals layered materials with low thermal conductivity and large power factor is important for the development of layered thermoelectric materials.Therefore,the novel van der Waals intercalated compound La_(2)Bi_(4)Cu_(2)O_(6)Se_(4),which is constructed by alternately stacking LaCuSeO and Bi_(2)O_(2)Se units along the c-axis in a 1:2 ratio,has designed for thermoelectric materials.The unique intercalated strategy leads to the four-band convergence at the valence band maximum,and the combination of multiple heavy band and light band,which significantly enhances the p-type doping power factor.The lattice thermal conductivities in La_(2)Bi_(4)Cu_(2)O_(6)Se_(4)and LaCuSeO compounds are accurately calculated by considering the coherence contributions of the anharmonic phonon reformulations and the off-diagonal term of the heat flux operator.The weak bond property of the Cu d-Se p bonding causes phonon softening,reducing the lattice thermal conductivity.The intercalated Bi atom has stereochemically active lone-pair electrons,which causes acoustic-optical coupling and produces strong fourth acoustic-optical phonon scattering,suppressing low-frequency phonon transport.The carrier relaxation time is rationalized by considering multiple carrier scattering mechanisms.The p-type doping La_(2)Bi_(4)Cu_(2)O_(6)Se_(4)achieves an average ZT of 2.3 at 700 K,and an optimal ZT of 2.7 along the in-plane direction.Our current work not only reveals the origin of the strong phonon scattering and large power factor of La_(2)Bi_(4)Cu_(2)O_(6)Se_(4)compound,but also provides theoretical guidance for the design of La-based layered oxides for thermoelectric applications.
基金supported by the National Natural Science Foundation of China (No.11534011)the National Key Research and Development Program of China (No.2017YFA0402300)
文摘Here an electron momentum spectroscopy study on the electronic structure of valence shell of iso-dichloroethylene molecule is reported. The experiment is carried out with a binary (e, 2e) spectrometer at incident electron energy of 1200 eV, employing noncoplanar symmetric arrangement. The binding energy spectra and electron momentum distributions (EMDs) of iso-dichloroethylene valence shell have been obtained. Theoretical EMDs are predicted with both Hartree-Fock and density functional theory methods, generally indicating good agreements with the measurement results. The interference effect is observed to significantly influence the EMDs of 2a2 and 5b2 Cl lone-pair orbitals.
基金National Natural Science Foundation of China(51872219)Fundamental Research Funds for the Central Universities(WUT:2020IVA097)Funds for Postdoctoral Innovative Research Posts in Hubei Province(20201jb010)。
