In this work,the Fukui functions of the two ~2P resonance states of Be,a ~2P resonance state of Mg~–,and a ~2D resonance state of Ca~– have been determined.The trajectories of these resonance states,in conjunction w...In this work,the Fukui functions of the two ~2P resonance states of Be,a ~2P resonance state of Mg~–,and a ~2D resonance state of Ca~– have been determined.The trajectories of these resonance states,in conjunction with the complex rotation of the Hamiltonian,were used to determine their wave functions.The electron densities,Fukui functions,and values of the hyper-radius<r^2>were computed from these wave functions.The Fukui functions have negative regions in the valence shell in addition to the inner shell regions,indicating screening effects of the outer temporary electron.Selected configuration interactions with up to quadruple excitations were used along the trajectories and for computing the final wave function.Based on this data,the densities,Fukui functions,and<r^2>were calculated.展开更多
Chemical reactivity towards electron transfer is captured by the Fukui function.However,this is not well defined when the system or its ions have degenerate or pseudo-degenerate ground states.In such a case,the first-...Chemical reactivity towards electron transfer is captured by the Fukui function.However,this is not well defined when the system or its ions have degenerate or pseudo-degenerate ground states.In such a case,the first-order chemical response is not independent of the perturbation and the correct response has to be computed using the mathematical formalism of perturbation theory for degenerate states.Spatialpseudo-degeneracy is ubiquitous in nanostructures with high symmetry and totally extended systems.Given the size of these systems,using degenerate-state perturbation theory is impractical because it requires the calculation of many excited states.Here we present an alternative to compute the chemical response of extended systems using models of local softness in terms of the local density of states.The local softness is approximately equal to the density of states at the Fermi level.However,such approximation leaves out the contribution of inner states.In order to include and weight the contribution of the states around the Fermi level,a model inspired by the long-range behavior of the local softness is presented.Single wall capped carbon nanotubes(SWCCNT) illustrate the limitation of the frontier orbital theory in extended systems.Thus,we have used a C360 SWCCNT to test the proposed model and how it compares with available models based on the local density of states.Interestingly,a simple Hü ckel approximation captures the main features of chemical response of these systems.Our results suggest that density-of-states models of the softness along simple tight binding Hamiltonians could be used to explore the chemical reactivity of more complex system,such a surfaces and nanoparticles.展开更多
Triacetone triperoxide (TATP) is more sensitive than diacetone diperoxide (DADP) in the solid-state explosion. To explain this reactivity difference, we analyzed the electronic structures and properties of the cry...Triacetone triperoxide (TATP) is more sensitive than diacetone diperoxide (DADP) in the solid-state explosion. To explain this reactivity difference, we analyzed the electronic structures and properties of the crystals of both compounds by using Ab initio method to calculate the structures of their individual molecules as well as their lattice structures and particularly calculating Nuclear Fukui function to gain insight into the sensitivity of the initial, rate-determining step of their decomposition. Our results indicate that TATP and DADP crystal structures exhibit significantly different electronic proper- ties. Most notably, the electronic structure of the TATP crystal shows asymmetry among its reactive oxygen atoms as supported by magnitudes of their nuclear Fukui functions. The greater explosion sensitivity of crystalline TATP may be attributed to the properties of its electronic structure. The electronic calculations provided valuable insight into the decomposition sensitivity difference between TATP and DADP crystals.展开更多
Atrazine(ATZ),as one of the most extensively employed organochlorine-based herbicides,exhibits persistence and environmental toxicity.Photocatalytic technology based on polymer carbon nitride is regarded as a sus-tain...Atrazine(ATZ),as one of the most extensively employed organochlorine-based herbicides,exhibits persistence and environmental toxicity.Photocatalytic technology based on polymer carbon nitride is regarded as a sus-tainable and promising approach for the degradation of emerging organic pollutants.Regrettably,the inherent shortcomings of pure carbon nitride greatly limit its practical application.Herein,S-doped carbon nitride was elaborately constructed for efficient degradation of ATZ.The removal efficiency of ATZ by the optimal sample(0.052 min^(-1))is 3.25 times as that of pure carbon nitride(0.016 min^(-1)).Experiments and DFT calculations show that S doping optimizes electronic structure of carbon nitride,which significantly enhances the spatial separation and transfer efficiency of photogenerated electrons and holes.Moreover,the reactive sites and degradation paths of ATZ were predicted by Fukui function and LC-MS determination.Our work provides an effective approach for the design of efficient photocatalysts to achieve efficient environmental remediation.展开更多
文摘In this work,the Fukui functions of the two ~2P resonance states of Be,a ~2P resonance state of Mg~–,and a ~2D resonance state of Ca~– have been determined.The trajectories of these resonance states,in conjunction with the complex rotation of the Hamiltonian,were used to determine their wave functions.The electron densities,Fukui functions,and values of the hyper-radius<r^2>were computed from these wave functions.The Fukui functions have negative regions in the valence shell in addition to the inner shell regions,indicating screening effects of the outer temporary electron.Selected configuration interactions with up to quadruple excitations were used along the trajectories and for computing the final wave function.Based on this data,the densities,Fukui functions,and<r^2>were calculated.
基金This work has been supported by FONDECYT grants 1140313 and 11150164. CC and PF acknowledge support by Financiamiento Basal para Centros Cientificos y Tecnologicos de Excelencia-FB0807, and project RC-130006 CILIS, granted by the Fondo de Innovacion para
文摘Chemical reactivity towards electron transfer is captured by the Fukui function.However,this is not well defined when the system or its ions have degenerate or pseudo-degenerate ground states.In such a case,the first-order chemical response is not independent of the perturbation and the correct response has to be computed using the mathematical formalism of perturbation theory for degenerate states.Spatialpseudo-degeneracy is ubiquitous in nanostructures with high symmetry and totally extended systems.Given the size of these systems,using degenerate-state perturbation theory is impractical because it requires the calculation of many excited states.Here we present an alternative to compute the chemical response of extended systems using models of local softness in terms of the local density of states.The local softness is approximately equal to the density of states at the Fermi level.However,such approximation leaves out the contribution of inner states.In order to include and weight the contribution of the states around the Fermi level,a model inspired by the long-range behavior of the local softness is presented.Single wall capped carbon nanotubes(SWCCNT) illustrate the limitation of the frontier orbital theory in extended systems.Thus,we have used a C360 SWCCNT to test the proposed model and how it compares with available models based on the local density of states.Interestingly,a simple Hü ckel approximation captures the main features of chemical response of these systems.Our results suggest that density-of-states models of the softness along simple tight binding Hamiltonians could be used to explore the chemical reactivity of more complex system,such a surfaces and nanoparticles.
基金This research was supported by NSF (DMR- 0449633). PPZ thanks the financial support by the National Natural Science Foundation of China (Grant No. 21403097) and the Fundamental Research Funds for the Central Universities (lzujbky-2014-182). The authors would like to thank Dr. Shaoxin Feng for his technical supports on this project. TL also thanks Dr. Shubin Liu (UNC) for sharing his insights on DFT.
文摘Triacetone triperoxide (TATP) is more sensitive than diacetone diperoxide (DADP) in the solid-state explosion. To explain this reactivity difference, we analyzed the electronic structures and properties of the crystals of both compounds by using Ab initio method to calculate the structures of their individual molecules as well as their lattice structures and particularly calculating Nuclear Fukui function to gain insight into the sensitivity of the initial, rate-determining step of their decomposition. Our results indicate that TATP and DADP crystal structures exhibit significantly different electronic proper- ties. Most notably, the electronic structure of the TATP crystal shows asymmetry among its reactive oxygen atoms as supported by magnitudes of their nuclear Fukui functions. The greater explosion sensitivity of crystalline TATP may be attributed to the properties of its electronic structure. The electronic calculations provided valuable insight into the decomposition sensitivity difference between TATP and DADP crystals.
基金support from National Key Research and Development Program of China(2022YFC3202402)the Fundamental Research Funds for the Cornell University(B230205044)+2 种基金Natural Science Foundation of China(51979081,52100179)Fundamental Research Funds for the Central Universities(B200202103)PAPD,Postgraduate Research&Practice Innovation Program of Jiangsu Province.
文摘Atrazine(ATZ),as one of the most extensively employed organochlorine-based herbicides,exhibits persistence and environmental toxicity.Photocatalytic technology based on polymer carbon nitride is regarded as a sus-tainable and promising approach for the degradation of emerging organic pollutants.Regrettably,the inherent shortcomings of pure carbon nitride greatly limit its practical application.Herein,S-doped carbon nitride was elaborately constructed for efficient degradation of ATZ.The removal efficiency of ATZ by the optimal sample(0.052 min^(-1))is 3.25 times as that of pure carbon nitride(0.016 min^(-1)).Experiments and DFT calculations show that S doping optimizes electronic structure of carbon nitride,which significantly enhances the spatial separation and transfer efficiency of photogenerated electrons and holes.Moreover,the reactive sites and degradation paths of ATZ were predicted by Fukui function and LC-MS determination.Our work provides an effective approach for the design of efficient photocatalysts to achieve efficient environmental remediation.