As the world’s first country to launch industrial revolution,the UK had once been at the peak of global power for a long term and exerted great inf luence on the shaping of modern
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
A comprehensive first principles study of III-Antimonide binary compounds is hardly found in literature. We report a broad study of structural and electronic properties of boron antimonide (BSb), aluminium antimoni...A comprehensive first principles study of III-Antimonide binary compounds is hardly found in literature. We report a broad study of structural and electronic properties of boron antimonide (BSb), aluminium antimonide (AlSb), gallium antimonide (GaSb) and indium antimonide (InSb) in zineblende phase based on density functional theory (DFT). Our calculations are based on Full-PotentiM Lineaxized Augmented Plane wave plus local orbitals (FP- L(APWq-lo)) method. Different forms of exchange-correlation energy functional and corresponding potential are employed for structural and electronic properties. Our computed results for lattice parameters, bulk moduli, their pressure derivatives, and cohesive energy are consistent with the available experimental data. Boron antimonide is found to be the hardest compound of this group. For band structure calculations, in addition to LDA and GGA, we used GGA-EV, an approximation employed by Engel and Vosko. The band gap results with GGA-EV are of significant improvement over the earlier work.展开更多
In this paper, the dynamical effeCts of divergent wind on the intraseasonal variability of atmospheric circulationover East Asia are analyzed by using the function of Rossby-wave source and the energy exchanging funct...In this paper, the dynamical effeCts of divergent wind on the intraseasonal variability of atmospheric circulationover East Asia are analyzed by using the function of Rossby-wave source and the energy exchanging function between divergent component and rotahonal component of the flow.The results analyzed from the observed data show that the advection of voracity by divergent wind caused by theheating due to the monsoon rainfall in the south to the Yangals River and the strong convective activities around thePhilippines may play an important role in the northward jump of westerly jet stream during the seasonal transitionfrom sprillg circulation to summer circulahon over East Asia. Due to the northward movement of the advechon ofvorticity by the divergent willd, the energy transformation from divergent component into rotational component canbe caused over the Yellow River basin and Northwest China and will cause the intensification of the zonal flow there.Thus, the jet stream abruptly shifts northward to North China.Moreover, the analysed results also show that the advection of vorticity by divergent wind caused by the heatingdue to the strong convective activities around the Philippines also plays an important role in the intraseasonal variability of the circulation over East Asia during the seasonal transition from summer to winter. With the southward'movement of the advection of vorticity by the divergent wind, the energy transformation from divergent componentinto rotational comPOnent can be caused over East Asia, espeially over the Yangtze-Huaihe River basin. Therefore,the jet stream gradually moves southward from North China to the YangtZe River basin.展开更多
Using the meta-generalized gradient approximation (meta-GGA) exchange correlation TPSS functional, the geo-metric structures, the relative stabilities, and the electronic properties of bimetallic AgnX (X=Au, Cu; n=...Using the meta-generalized gradient approximation (meta-GGA) exchange correlation TPSS functional, the geo-metric structures, the relative stabilities, and the electronic properties of bimetallic AgnX (X=Au, Cu; n=1-8) clusters are systematically investigated and compared with those of pure silver clusters. The optimized structures show that the transition point from preferentially planar to three-dimensional structure occurs at n = 6 for the AgnAu clusters, and at n = 5 for AgnCu clusters. For different-sized AgnX clusters, one X (X=Au or Cu) atom substituted Agn+l structure is a dominant growth pattern. The calculated fragmentation energies, second-order differences in energies, and the highest occupied molecular orbital-lowest unoccupied molecular orbital (HOMO LUMO) energy gaps show interesting odd-even oscillation behaviours, indicating that Ag2,4,6,s and Agl,3,5,7X (X=Au, Cu) clusters keep high stabilities in comparison with their neighbouring clusters. The natural population analysis reveals that the charges transfer from the Agn host to the impurity atom except for the Ag2Cu cluster. Moreover, vertical ionization potential (VIP), vertical electronic affinity (VEA), and chemical hardness (η) are discussed and compared in depth. The same odd even oscillations are found for the VIP and η of the AgnX (X=Au, Cu; n=1-8) clusters.展开更多
By using field-survey hydrological data of the related control stations in Dongting Lake and the Yangtze River mainstream in 1951-2010, the evolution characters of water exchange abilities between the two. water bodie...By using field-survey hydrological data of the related control stations in Dongting Lake and the Yangtze River mainstream in 1951-2010, the evolution characters of water exchange abilities between the two. water bodies and their response to the operation of the Three Gorges Reservoir (TGR) from different time scales are analyzed based on their hydraulic relations. The results are shown as follows. Firstly, during July-September, the replenishment ability of Three Outlets to Dongting Lake is stronger, and in January-March, the replenishment ability of Dongting Lake to Yangtze River is stronger. Secondly, there has been an obvious inter-decadal wave on the water exchange coefficient between Dongting Lake and Yangtze River. In 1951-1958 and 1959-1968, the replenishment ability of Three Outlets to Dongting Lake was stronger, but in 2003-2010, the replenishment ability of Dongting Lake to Yangtze River has been strengthened. Thirdly, the spill-division ability of Three Outlets weakens, and the water of Dongting Lake coming from Three Outlets decreases either in typical years or under different dispatching modes of the TGR after the operation of the Three Gorges Reservoir. Furthermore, the water of Dongting Lake coming from Four Rivers takes the dominant position, which obviously enhances the replenishment ability of Dongting Lake to Yangtze River. Fourthly, if the effect of the runoff fluctuation in the basin is not considered, the evolution characters of the exchange capacities and the exchange process between Dongting Lake and Yangtze River in different time scales are generally changed with the variation of the water exchange amount between them, although the factors influencing the water exchange capacities between them is very complex. These show that there is an in-line growth or decline relation between the river-lake water exchange ability and the river-lake water exchange amount.展开更多
As the rate-determining step in native chemical ligation reactions, the thiol–thioester exchange step is important in determining the efficiency of the ligations of peptides. In the present study, systematic theoreti...As the rate-determining step in native chemical ligation reactions, the thiol–thioester exchange step is important in determining the efficiency of the ligations of peptides. In the present study, systematic theoretical calculations were carried out on the relationships between the structure of different thioesters and the free energy barriers of the thiol–thioester exchange step. According to the calculation results, the thiol–thioester exchange step is disfavored by the steric hindrance around the carbonyl center, while the electronic effect(i.e. conjugation and hyper-conjugation effects) becomes important when the steric hindrance is insignificant.展开更多
文摘As the world’s first country to launch industrial revolution,the UK had once been at the peak of global power for a long term and exerted great inf luence on the shaping of modern
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.
文摘A comprehensive first principles study of III-Antimonide binary compounds is hardly found in literature. We report a broad study of structural and electronic properties of boron antimonide (BSb), aluminium antimonide (AlSb), gallium antimonide (GaSb) and indium antimonide (InSb) in zineblende phase based on density functional theory (DFT). Our calculations are based on Full-PotentiM Lineaxized Augmented Plane wave plus local orbitals (FP- L(APWq-lo)) method. Different forms of exchange-correlation energy functional and corresponding potential are employed for structural and electronic properties. Our computed results for lattice parameters, bulk moduli, their pressure derivatives, and cohesive energy are consistent with the available experimental data. Boron antimonide is found to be the hardest compound of this group. For band structure calculations, in addition to LDA and GGA, we used GGA-EV, an approximation employed by Engel and Vosko. The band gap results with GGA-EV are of significant improvement over the earlier work.
文摘In this paper, the dynamical effeCts of divergent wind on the intraseasonal variability of atmospheric circulationover East Asia are analyzed by using the function of Rossby-wave source and the energy exchanging function between divergent component and rotahonal component of the flow.The results analyzed from the observed data show that the advection of voracity by divergent wind caused by theheating due to the monsoon rainfall in the south to the Yangals River and the strong convective activities around thePhilippines may play an important role in the northward jump of westerly jet stream during the seasonal transitionfrom sprillg circulation to summer circulahon over East Asia. Due to the northward movement of the advechon ofvorticity by the divergent willd, the energy transformation from divergent component into rotational component canbe caused over the Yellow River basin and Northwest China and will cause the intensification of the zonal flow there.Thus, the jet stream abruptly shifts northward to North China.Moreover, the analysed results also show that the advection of vorticity by divergent wind caused by the heatingdue to the strong convective activities around the Philippines also plays an important role in the intraseasonal variability of the circulation over East Asia during the seasonal transition from summer to winter. With the southward'movement of the advection of vorticity by the divergent wind, the energy transformation from divergent componentinto rotational comPOnent can be caused over East Asia, espeially over the Yangtze-Huaihe River basin. Therefore,the jet stream gradually moves southward from North China to the YangtZe River basin.
基金supported by the National Natural Science Foundation of China (Grant Nos. 10774103 and 10974138)
文摘Using the meta-generalized gradient approximation (meta-GGA) exchange correlation TPSS functional, the geo-metric structures, the relative stabilities, and the electronic properties of bimetallic AgnX (X=Au, Cu; n=1-8) clusters are systematically investigated and compared with those of pure silver clusters. The optimized structures show that the transition point from preferentially planar to three-dimensional structure occurs at n = 6 for the AgnAu clusters, and at n = 5 for AgnCu clusters. For different-sized AgnX clusters, one X (X=Au or Cu) atom substituted Agn+l structure is a dominant growth pattern. The calculated fragmentation energies, second-order differences in energies, and the highest occupied molecular orbital-lowest unoccupied molecular orbital (HOMO LUMO) energy gaps show interesting odd-even oscillation behaviours, indicating that Ag2,4,6,s and Agl,3,5,7X (X=Au, Cu) clusters keep high stabilities in comparison with their neighbouring clusters. The natural population analysis reveals that the charges transfer from the Agn host to the impurity atom except for the Ag2Cu cluster. Moreover, vertical ionization potential (VIP), vertical electronic affinity (VEA), and chemical hardness (η) are discussed and compared in depth. The same odd even oscillations are found for the VIP and η of the AgnX (X=Au, Cu; n=1-8) clusters.
基金National Natural Science Foundation of China, No.41071067 Construct Program of the Key Discipline of the Physical Geography in Hunan Province
文摘By using field-survey hydrological data of the related control stations in Dongting Lake and the Yangtze River mainstream in 1951-2010, the evolution characters of water exchange abilities between the two. water bodies and their response to the operation of the Three Gorges Reservoir (TGR) from different time scales are analyzed based on their hydraulic relations. The results are shown as follows. Firstly, during July-September, the replenishment ability of Three Outlets to Dongting Lake is stronger, and in January-March, the replenishment ability of Dongting Lake to Yangtze River is stronger. Secondly, there has been an obvious inter-decadal wave on the water exchange coefficient between Dongting Lake and Yangtze River. In 1951-1958 and 1959-1968, the replenishment ability of Three Outlets to Dongting Lake was stronger, but in 2003-2010, the replenishment ability of Dongting Lake to Yangtze River has been strengthened. Thirdly, the spill-division ability of Three Outlets weakens, and the water of Dongting Lake coming from Three Outlets decreases either in typical years or under different dispatching modes of the TGR after the operation of the Three Gorges Reservoir. Furthermore, the water of Dongting Lake coming from Four Rivers takes the dominant position, which obviously enhances the replenishment ability of Dongting Lake to Yangtze River. Fourthly, if the effect of the runoff fluctuation in the basin is not considered, the evolution characters of the exchange capacities and the exchange process between Dongting Lake and Yangtze River in different time scales are generally changed with the variation of the water exchange amount between them, although the factors influencing the water exchange capacities between them is very complex. These show that there is an in-line growth or decline relation between the river-lake water exchange ability and the river-lake water exchange amount.
基金NSFC (No. 21202006)FRFCU (No. FRF-TP14-015A2) for financial supports and Super-computer Center of Shanghai and Shenzhen for technical supports
文摘As the rate-determining step in native chemical ligation reactions, the thiol–thioester exchange step is important in determining the efficiency of the ligations of peptides. In the present study, systematic theoretical calculations were carried out on the relationships between the structure of different thioesters and the free energy barriers of the thiol–thioester exchange step. According to the calculation results, the thiol–thioester exchange step is disfavored by the steric hindrance around the carbonyl center, while the electronic effect(i.e. conjugation and hyper-conjugation effects) becomes important when the steric hindrance is insignificant.