We have investigated the resonant propagation of femtosecond laser pulse in 4-trans-[p-（N, N-Di-n-butylamino）- p-stilbenyl vinyl] pyridine medium with permanent dipole moments. The electronic structures and paramete...We have investigated the resonant propagation of femtosecond laser pulse in 4-trans-[p-（N, N-Di-n-butylamino）- p-stilbenyl vinyl] pyridine medium with permanent dipole moments. The electronic structures and parameters for the compound have been calculated by using density functional theory. In the optical regime, there is one charge-transfer state, and the molecule can thus be simplified as a two-level system. Both the one- and two-photon transitions occur between the ground and charge-transfer states. The numerical results show that the permanent dipole moments have an obvious effect on the propagation of the ultrashort pulse laser. The ideal self-induced transparency disappears for 2π pulse, and second harmonic spectral components occur significantly due to the two-photon absorption process. For the 6π pulse, continuum frequency generation is produced and a shorter duration pulse in time domain with 465 as is obtained.展开更多
With the concept of super-atom, first principles calculations propose a new type of super stable cage clusters AlnH3n that are much more energetic stable than the well established clusters, AlnHn＋2. In the new cluste...With the concept of super-atom, first principles calculations propose a new type of super stable cage clusters AlnH3n that are much more energetic stable than the well established clusters, AlnHn＋2. In the new clusters, the aluminum core-frame acts as a super-atom with n vertexes and 2n A1-A1 edges, which allow to adsorb n hydrogen atoms at the top-site and 2n at the bridge-site. Using Al12H36 as the basic unit, stable chain structures, （Al12H36）m, have been constructed following the same connection mechanism as for （A1H3）n linear polymeric structures. Apart from high hydrogen percentage per molecule, calculations have shown that these new clusters possess large heat of formation values and their combustion heat is about 4.8 times of the methane, making them a promising high energy density material.展开更多
Recently, molecular electronics has become increasingly important. By applying the hybrid density functional theory coupled with the Green＇s function method, the current-voltage characteristics of the molecular junct...Recently, molecular electronics has become increasingly important. By applying the hybrid density functional theory coupled with the Green＇s function method, the current-voltage characteristics of the molecular junctions composed of gold-porphyrin-gold and gold-copper porphyrin-gold were investigated. The role of the metal coordination effect in organic molecular electron transport was highlighted. Although the thresholds of the bias voltage for both molecules were almost the same, approximately 0. 9 V, the metal compound showed a larger increase in current because of the metal-coordination-enhanced molecule-electrode coupling in the frontier molecular orbitals.展开更多
Coherent electronic transport properties of silver-C60-silver molecular junctions in different configurations are studied using hybrid density function theory. The experimentally measured current flows of （760 molecu...Coherent electronic transport properties of silver-C60-silver molecular junctions in different configurations are studied using hybrid density function theory. The experimentally measured current flows of （760 molecules adsorbed on the silver surface are well reproduced by theoretical calculations. It is found that the current-voltage characteristics of the molecular junctions depend strongly on the configurations of the junctions. Transmission spectra combined with density of states can help us to understand in depth the transport properties. Different kinds of electrode construction are also discussed. With the help of the calculation, two possible configurations of silver-C60-silver molecular junctions are suggested.展开更多
The elastic scattering Green function method has been developed to describe the Ⅰ-Ⅴ characteristics of molecular wires.The molecular electronic structure and the interaction between the molecule and the gold surface...The elastic scattering Green function method has been developed to describe the Ⅰ-Ⅴ characteristics of molecular wires.The molecular electronic structure and the interaction between the molecule and the gold surface are two key factors for the charge transport properties of mo- lecular wires in the formulas.An ab initio calculation at the hybrid density functional theory level is carried out to obtain the electronic structure of 4-4′-dimercaptodibenzene molecule.The frontier orbit theory and the perturbation theory are employed to determine the constant of the interaction energy between molecule and surface quantitatively.The numerical results show that the bonding between the sulfur atom and the gold atoms corresponds mainly to the covalent bond.Some mo- lecular orbits are extended over molecule and gold cluster that certainly give channels for the charge transport,other molecular orbits are localized and the charge transport can take place by turinel mechanism.At zero bias region,there exists a current gap.With the increasing bias,the conductance of the wire takes a shape of plateaus.展开更多
基金Project supported by the Shandong Natural Science Foundation （Grant No Y2004A08）, the University Doctoral Subject Special Science and Technology Foundation （Grant No 20040445001） and The Key Laboratory for High Intensity 0ptics of Shanghai Institute of 0ptics and Fine Mechanics, Chinese Academy of Sciences.
文摘We have investigated the resonant propagation of femtosecond laser pulse in 4-trans-[p-（N, N-Di-n-butylamino）- p-stilbenyl vinyl] pyridine medium with permanent dipole moments. The electronic structures and parameters for the compound have been calculated by using density functional theory. In the optical regime, there is one charge-transfer state, and the molecule can thus be simplified as a two-level system. Both the one- and two-photon transitions occur between the ground and charge-transfer states. The numerical results show that the permanent dipole moments have an obvious effect on the propagation of the ultrashort pulse laser. The ideal self-induced transparency disappears for 2π pulse, and second harmonic spectral components occur significantly due to the two-photon absorption process. For the 6π pulse, continuum frequency generation is produced and a shorter duration pulse in time domain with 465 as is obtained.
基金This work was supported by the Swedish Research Council, Swedish National Infrastructure for Computing, the National Natural Science Foundation of China （No.10534010 and No.20925311）, the Funda-mental Research Funds for the Central Universities （No.201103255）, and the China Scholarship Council.
文摘With the concept of super-atom, first principles calculations propose a new type of super stable cage clusters AlnH3n that are much more energetic stable than the well established clusters, AlnHn＋2. In the new clusters, the aluminum core-frame acts as a super-atom with n vertexes and 2n A1-A1 edges, which allow to adsorb n hydrogen atoms at the top-site and 2n at the bridge-site. Using Al12H36 as the basic unit, stable chain structures, （Al12H36）m, have been constructed following the same connection mechanism as for （A1H3）n linear polymeric structures. Apart from high hydrogen percentage per molecule, calculations have shown that these new clusters possess large heat of formation values and their combustion heat is about 4.8 times of the methane, making them a promising high energy density material.
基金Supported by the National Natural Science Foundation of China(Nos 90301001 and 10425420) and the Supercomputing Center of the Chinese Academy of Sciences
文摘Recently, molecular electronics has become increasingly important. By applying the hybrid density functional theory coupled with the Green＇s function method, the current-voltage characteristics of the molecular junctions composed of gold-porphyrin-gold and gold-copper porphyrin-gold were investigated. The role of the metal coordination effect in organic molecular electron transport was highlighted. Although the thresholds of the bias voltage for both molecules were almost the same, approximately 0. 9 V, the metal compound showed a larger increase in current because of the metal-coordination-enhanced molecule-electrode coupling in the frontier molecular orbitals.
文摘Coherent electronic transport properties of silver-C60-silver molecular junctions in different configurations are studied using hybrid density function theory. The experimentally measured current flows of （760 molecules adsorbed on the silver surface are well reproduced by theoretical calculations. It is found that the current-voltage characteristics of the molecular junctions depend strongly on the configurations of the junctions. Transmission spectra combined with density of states can help us to understand in depth the transport properties. Different kinds of electrode construction are also discussed. With the help of the calculation, two possible configurations of silver-C60-silver molecular junctions are suggested.
基金the National Natural Science Foundation of China(Grant No.10274044)Shandong Science Foundation(Grant No.Y2000A03)the Foundation for Outstanding Teachers of the Education Ministry of China.
文摘The elastic scattering Green function method has been developed to describe the Ⅰ-Ⅴ characteristics of molecular wires.The molecular electronic structure and the interaction between the molecule and the gold surface are two key factors for the charge transport properties of mo- lecular wires in the formulas.An ab initio calculation at the hybrid density functional theory level is carried out to obtain the electronic structure of 4-4′-dimercaptodibenzene molecule.The frontier orbit theory and the perturbation theory are employed to determine the constant of the interaction energy between molecule and surface quantitatively.The numerical results show that the bonding between the sulfur atom and the gold atoms corresponds mainly to the covalent bond.Some mo- lecular orbits are extended over molecule and gold cluster that certainly give channels for the charge transport,other molecular orbits are localized and the charge transport can take place by turinel mechanism.At zero bias region,there exists a current gap.With the increasing bias,the conductance of the wire takes a shape of plateaus.
