采用单双激发运动方程耦合簇(EOM-CCSD)以及多个包含迭代三激发在内的运动方程耦合簇变体(EOM-CCSDT-i,i=1a,1b,2,3和EOM-CC3)计算了HOF价层垂直电离势(VIP).在EOM-CCSD水平上优化出各价层电离态结构,得到绝热电离势(AIP),进一步计算出...采用单双激发运动方程耦合簇(EOM-CCSD)以及多个包含迭代三激发在内的运动方程耦合簇变体(EOM-CCSDT-i,i=1a,1b,2,3和EOM-CC3)计算了HOF价层垂直电离势(VIP).在EOM-CCSD水平上优化出各价层电离态结构,得到绝热电离势(AIP),进一步计算出谐振频率.同时对称匹配簇组态相互作用(SAC/SAC-CI)也被应用到部分计算.结果显示:EOM-CC3、EOM-CCSDT-3计算的VIP接近于全三激发运动方程耦合簇EOM-CCSDT结果;EOM-CC与SAC-CI值基本一致;同时发现HOF光电子能谱实验在2A'态指认上有误并重新进行归属.HOF的第三VIP应为16.9 e V,而非光电子能谱实验测得的16.0 e V.展开更多
Shaping either the spatial or the spectral output of a nonlinear interaction is accomplished by introducing basic concepts of computer-generated holography into the nonlinear optics regime. The possibilities of arbitr...Shaping either the spatial or the spectral output of a nonlinear interaction is accomplished by introducing basic concepts of computer-generated holography into the nonlinear optics regime. The possibilities of arbitrarily spatially shaping the result of a nonlinear interaction are presented for different phase-matching schemes allowing for both one- and two-dimensional shaping. Shaping the spectrum of a beam in nonlinear interaction is also possible by utilizing similar holographic techniques. The novel and complete control of the output of a nonlinear interaction opens exciting options in the fields of particle manipulation, optical communications, spectroscopy and quantum information.展开更多
Interactions between disruptive colouration and the match between prey and background spot size were manipulated in two experiments that used time taken by human ＇predators＇ to find artificial prey （virtual crab mo...Interactions between disruptive colouration and the match between prey and background spot size were manipulated in two experiments that used time taken by human ＇predators＇ to find artificial prey （virtual crab morphs） against heterogeneous backgrounds as a measure of the their camouflage. Experiment 1, in which the spots and their placement imitated the arrangement on the crab Carcinus maenas, tested whether high and low contrast spots touching the body outline （disruptive ＇edge＇ morphs） made the artificial prey more difficult to detect than when the spots did not touch the outline （non-disruptive ＇inner＇ morphs） against three different backgrounds： ＇small＇, ＇middle＇ and ＇large＇ spot size. In Experiment 2, the range of spot sizes and their positions （＇edge＇ and ＇inner＇） on the crab morphs were varied to determine the most effective combination against the ＇mid- dle＇ background. Altogether, 640 volunteers participated in these computer trials, representing a high degree of independent replication. All patterned morphs were significantly harder to detect than plain morphs, indicating that possessing at least some degree of background matching can provide camouflage. Both experiments demonstrated that various morphs, though not having the same spot sizes as the background, had similar or better survivorship as those with matching spot sizes--indicating that opti- mal camouflage did not come from background matching alone. In Experiment 2, edge-disrupted morphs consistently took longer to find than their non-disruptive counterparts. The relative effects of edge disruption, contrast, and background/prey spot size are clearly context-dependent, highlighting the complexity of prey concealment [Current Zoology 61 （4）： 718-728, 2015].展开更多
Applying a fully nonlinear numerical scheme with second-order temporal and spatial precision,nonlinear interactions of gravity waves are simulated and the matching relationships of the wavelengths and frequencies of t...Applying a fully nonlinear numerical scheme with second-order temporal and spatial precision,nonlinear interactions of gravity waves are simulated and the matching relationships of the wavelengths and frequencies of the interacting waves are discussed.In resonant interactions,the wavelengths of the excited wave are in good agreement with the values derived from sum or difference resonant conditions,and the frequencies of the three waves also satisfy the matching condition.Since the interacting waves obey the resonant conditions,resonant interactions have a reversible feature that for a resonant wave triad,any two waves are selected to be the initial perturbations,and the third wave can then be excited through sum or difference resonant interaction.The numerical results for nonresonant triads show that in nonresonant interactions,the wave vectors tend to approximately match in a single direction,generally in the horizontal direction.The frequency of the excited wave is close to the matching value,and the degree of mismatching of frequencies may depend on the combined effect of both the wavenumber and frequency mismatches that should benefit energy exchange to the greatest extent.The matching and mismatching relationships in nonresonant interactions differ from the results of weak interaction theory that the wave vectors are required to satisfy the resonant matching condition but the frequencies are permitted to mismatch and oscillate with amplitude of half the mismatching frequency.Nonresonant excitation has an irreversible characteristic,which is different from what is found for the resonant interaction.For specified initial primary and secondary waves,it is difficult to predict the values of the mismatching wavenumber and frequency for the excited wave owing to the complexity.展开更多
Terahertz(THz) generation by periodically-poled RbTiOPO_4(PPRTP) with a quasi-phase-matching scheme based on cascaded difference frequency generation(DFG) processes is theoretically analyzed. The cascaded Stokes and a...Terahertz(THz) generation by periodically-poled RbTiOPO_4(PPRTP) with a quasi-phase-matching scheme based on cascaded difference frequency generation(DFG) processes is theoretically analyzed. The cascaded Stokes and anti-Stokes interaction processes are investigated from coupled wave equations. The THz intensities and quantum conversion efficiency are calculated. Compared with that of non-cascaded DFG processes, the THz intensity in 7-order cascaded DFG processes is increased to 2.95 times. The quantum conversion efficiency of 149.9% in cascaded processes can be realized, which exceeds the Manley-Rowe limit.展开更多
文摘采用单双激发运动方程耦合簇(EOM-CCSD)以及多个包含迭代三激发在内的运动方程耦合簇变体(EOM-CCSDT-i,i=1a,1b,2,3和EOM-CC3)计算了HOF价层垂直电离势(VIP).在EOM-CCSD水平上优化出各价层电离态结构,得到绝热电离势(AIP),进一步计算出谐振频率.同时对称匹配簇组态相互作用(SAC/SAC-CI)也被应用到部分计算.结果显示:EOM-CC3、EOM-CCSDT-3计算的VIP接近于全三激发运动方程耦合簇EOM-CCSDT结果;EOM-CC与SAC-CI值基本一致;同时发现HOF光电子能谱实验在2A'态指认上有误并重新进行归属.HOF的第三VIP应为16.9 e V,而非光电子能谱实验测得的16.0 e V.
基金supported by the Israel Science Foundation(1310/13)the Israeli Ministry of Science,Technology and Space in the framework of the Israel–Italy bi-national collaboration program
文摘Shaping either the spatial or the spectral output of a nonlinear interaction is accomplished by introducing basic concepts of computer-generated holography into the nonlinear optics regime. The possibilities of arbitrarily spatially shaping the result of a nonlinear interaction are presented for different phase-matching schemes allowing for both one- and two-dimensional shaping. Shaping the spectrum of a beam in nonlinear interaction is also possible by utilizing similar holographic techniques. The novel and complete control of the output of a nonlinear interaction opens exciting options in the fields of particle manipulation, optical communications, spectroscopy and quantum information.
文摘Interactions between disruptive colouration and the match between prey and background spot size were manipulated in two experiments that used time taken by human ＇predators＇ to find artificial prey （virtual crab morphs） against heterogeneous backgrounds as a measure of the their camouflage. Experiment 1, in which the spots and their placement imitated the arrangement on the crab Carcinus maenas, tested whether high and low contrast spots touching the body outline （disruptive ＇edge＇ morphs） made the artificial prey more difficult to detect than when the spots did not touch the outline （non-disruptive ＇inner＇ morphs） against three different backgrounds： ＇small＇, ＇middle＇ and ＇large＇ spot size. In Experiment 2, the range of spot sizes and their positions （＇edge＇ and ＇inner＇） on the crab morphs were varied to determine the most effective combination against the ＇mid- dle＇ background. Altogether, 640 volunteers participated in these computer trials, representing a high degree of independent replication. All patterned morphs were significantly harder to detect than plain morphs, indicating that possessing at least some degree of background matching can provide camouflage. Both experiments demonstrated that various morphs, though not having the same spot sizes as the background, had similar or better survivorship as those with matching spot sizes--indicating that opti- mal camouflage did not come from background matching alone. In Experiment 2, edge-disrupted morphs consistently took longer to find than their non-disruptive counterparts. The relative effects of edge disruption, contrast, and background/prey spot size are clearly context-dependent, highlighting the complexity of prey concealment [Current Zoology 61 （4）： 718-728, 2015].
基金supported by National Natural Science Foundation of China (Grant Nos. 41074110,41174133 and 40825013)National Basic Research Program of China (Grant No. 2012CB825605)+2 种基金Ocean Public Welfare Scientific Research Project,State Oceanic Administration People’s Republic of China (Grant No. 201005017)China Meteorological Administration (Grant No. GYHY201106011)Fundamental Research Funds for the Central Universities
文摘Applying a fully nonlinear numerical scheme with second-order temporal and spatial precision,nonlinear interactions of gravity waves are simulated and the matching relationships of the wavelengths and frequencies of the interacting waves are discussed.In resonant interactions,the wavelengths of the excited wave are in good agreement with the values derived from sum or difference resonant conditions,and the frequencies of the three waves also satisfy the matching condition.Since the interacting waves obey the resonant conditions,resonant interactions have a reversible feature that for a resonant wave triad,any two waves are selected to be the initial perturbations,and the third wave can then be excited through sum or difference resonant interaction.The numerical results for nonresonant triads show that in nonresonant interactions,the wave vectors tend to approximately match in a single direction,generally in the horizontal direction.The frequency of the excited wave is close to the matching value,and the degree of mismatching of frequencies may depend on the combined effect of both the wavenumber and frequency mismatches that should benefit energy exchange to the greatest extent.The matching and mismatching relationships in nonresonant interactions differ from the results of weak interaction theory that the wave vectors are required to satisfy the resonant matching condition but the frequencies are permitted to mismatch and oscillate with amplitude of half the mismatching frequency.Nonresonant excitation has an irreversible characteristic,which is different from what is found for the resonant interaction.For specified initial primary and secondary waves,it is difficult to predict the values of the mismatching wavenumber and frequency for the excited wave owing to the complexity.
基金supported by the National Natural Science Foundation of China(Nos.61201101,61601183 and 61205003)the Young Backbone Teachers in University of Henan Province(No.2014GGJS-065)+1 种基金the Foundation and Advanced Technology Research Program of Henan Province(No.162300410269)the Program for Innovative Research Team(in Science and Technology)in University of Henan Province(No.16IRTSTHN017)
文摘Terahertz(THz) generation by periodically-poled RbTiOPO_4(PPRTP) with a quasi-phase-matching scheme based on cascaded difference frequency generation(DFG) processes is theoretically analyzed. The cascaded Stokes and anti-Stokes interaction processes are investigated from coupled wave equations. The THz intensities and quantum conversion efficiency are calculated. Compared with that of non-cascaded DFG processes, the THz intensity in 7-order cascaded DFG processes is increased to 2.95 times. The quantum conversion efficiency of 149.9% in cascaded processes can be realized, which exceeds the Manley-Rowe limit.
