Theoretical studies of the structural,electronic and optical properties of carbazole‐based compounds

Carbazole derivatives have drawn increasing attention recently in organic electronic device applications because of their particular optoelectronic properties. An in‐depth theoretical investigation was elaborated in this paper to reveal the molecular structures, optoelectronic properties, and the structure‐property relationships of different carbazole‐linked functional groups. The geometric and electronic structures in ground and the mobility for the hole and electron are both calculated by density functional theory method. The excited‐state geometries of these compounds were obtained through Single‐excitation Configuration Interaction method, and time‐dependent density functional theory calculation results described the absorption and emission spectra properties, respectively. Some conclusions are as follows: (1) enlarging the π‐conjugated area, the corresponding spectra red shifted markedly; (2) by introducing the electron‐donor such as carbazole, the spectra blue shifted slightly; (3) compared with compound 1, the spectra for these compounds are hardly influenced by introducing an electron‐acceptor or heterocyclic substitution. On all accounts, these compounds are interesting optoelectronic functional materials. On the basis of their structural modifiability, the arylamine derivatives substituted carbazole compounds have great potential in the applications of organic light‐emitting diodes, organic solar cells, and sensors. Copyright © 2011 John Wiley & Sons, Ltd.     

Mixed Valence Tungsten (IV,V) Compounds with Layered Structures (Part IV): Syntheses,Crystal Structures,and Conductivity of BiX2[W2O2X6] (X = Cl,Br)

The reaction of metallic bismuth with either tungsten tetrachlorideoxide WOCl₄ at 650 K or tungsten tetrabromideoxide WOBr₄ at 670 K, respectively, leads to BiX₂[W₂O₂X₆] (X = Cl, Br) as black, lustrous crystal needles. The crystal structure determinations (triclinic, P$\bar{1}$ ) show the two isotypic structures to be closely related to Hg_0.55[W₂O₂Cl₆] with the presence of 1D‐polymeric W₂O₂X₆ double strands. Dinuclear [Bi₂X₄]²⁺ cations are embedded in the host structure via secondary W–X ··· Bi bonds. Unlike the other members of theM_y[W₂O₂X₆] structure family, which crystallize monoclinic and show crystallographic equivalent tungsten atoms, BiX₂[W₂O₂X₆] has independent tungsten sites. Nevertheless, an assignment of an individual oxidation state to the tungsten atoms within the W₂ group (W–W 2.8321(4) Å for X = Cl, 2.8985(4) Å for X = Br) is not possible and a dynamic intervalent state W(IV, V) is assumed. Electrical conductivity measurements for BiCl₂[W₂O₂Cl₆] show semi‐conductive behavior with a very small band gap of 70 meV and a high conductivity of around 0.5 Ω^–1cm^–1 at temperatures above 220 K. A temperature dependence of the activation energy of charge transport is present and interpreted by the Varshni model.     

ERKALE—A flexible program package for X‐ray properties of atoms and molecules

ERKALE is a novel software program for computing X‐ray properties, such as ground‐state electron momentum densities, Compton profiles, and core and valence electron excitation spectra of atoms and molecules. The program operates at Hartree–Fock or density‐functional level of theory and supports Gaussian basis sets of arbitrary angular momentum and a wide variety of exchange‐correlation functionals. ERKALE includes modern convergence accelerators such as Broyden and ADIIS and it is suitable for general use, as calculations with thousands of basis functions can routinely be performed on desktop computers. Furthermore, ERKALE is written in an object oriented manner, making the code easy to understand and to extend to new properties while being ideal also for teaching purposes. © 2012 Wiley Periodicals, Inc.     

Interesting periodic variations in physical and chemical properties of homonuclear diatomic molecules

We carry out a systematic study of various ground state and response properties of homonuclear diatomic molecules (from hydrogen to rubidium, including transition metals) as a function of atomic number of constituent atoms. We perform the ground state and response property calculations by using state of the art density functional theory/time dependent density functional theory. We observe that several properties of homonuclear diatomic molecules show periodic variations along rows and columns of the periodic table. The periodic variations in the ground state properties of diatomic molecules may be explained by the nature and type of the bond that exists between the constituent atoms. Similarly, the periodic variations in the response properties such as static dipole polarizability and strength of the van der Waals interaction between diatomic molecules have been correlated with the variations in metallic/nonmetallic character of the elements along the periodic table. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2012     

Exploring sequential quantum adiabatic switching across supersymmetric partners for finding the eigenstates of a system

We demonstrate that one can exhaustively determine the n‐bound eigenstates of a Hamiltonian H by constructing a sequence of supersymmetric (SUSY) partner Hamiltonians and invoking a time‐dependent quantum adiabatic switching algorithm for passage from the ground state of one to the other. The ground states of the initial pair H⁽⁰⁾ and H⁽¹⁾ are constructed by solving the Riccati equation for the superpotential ?⁽⁰⁾ for H⁽⁰⁾ and adiabatically switching from the ground state Ψ of H⁽⁰⁾ to the ground state Ψ of H⁽¹⁾. The charge operator Q is then used to recover the first excited state Ψ of H⁽⁰⁾. The procedure is repeated for the ground states of SUSY pairs H^{(n + 1)} and H^{(n + 2)}, and appropriate charge operators lead to the excited states Ψ of H⁽⁰⁾ with , thereby exhausting the full eigenspectrum of H⁽⁰⁾. The workability of the proposed method is shown with several well‐known examples. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2011     

Quantum mechanical study on plasmon resonances in small ring clusters

The collectivity of the electronic motion in small sodium clusters with ring structure is studied by time‐dependent density functional theory. The formation and development of collective resonances in the absorption spectra were obtained as a function of the ring radius. In small ring clusters, besides the lower‐energy mode and the higher‐energy mode, there is another plasmon resonance mode, that is, the reverse two‐dipole mode. For the reverse two‐dipole mode, the formations of these two dipoles are due to the external field inducement and the shielding effect, although the resonant excitation is mainly due to the coupling effect of the electrons of these two dipoles. © 2012 Wiley Periodicals, Inc.     

Dynamic analysis of an SIR epidemic model with state dependent pulse vaccination

An SIR epidemic model with state dependent pulse vaccination is proposed in this paper. Using the Poincaré map, the differential inequality and the method of qualitative analysis, we prove the existence and the stability of positive order-1 or order-2 periodic solution for this model. Moreover, we show that there is no periodic solution with order larger than or equal to three. Numerical simulations are carried out to illustrate the feasibility of our main results and the suitability of state dependent pulse vaccination is also discussed.     

率相关本构方程积分新算法

提出一种积分率相关本构方程的隐式积分新算法,引入0～1范围内的缩放因子λ对本构方程进行间接求解,可以避免直接求解等效塑性应变或等效塑性应变率时,由于其数值过大或过小而造成的收敛困难或收敛失败,实现对率相关本构方程的快速准确求解.以B-P统一本构方程及双曲正弦本构方程为例,验证了算法的可行性.结果表明,新算法对于准静态变形条件下的无硬化本构方程也可以得出准确的解.     

Periodic boundary value problems for first-order integro-differential equations of mixed type

ＩｎｔｒｏｄｕｃｔｉｏｎＣｏｎｓｉｄｅｒｔｈｅｆｏｌｌｏｗｉｎｇｐｅｒｉｏｄｉｃｂｏｕｎｄａｒｙｖａｌｕｅｐｒｏｂｌｅｍ(ＰＢＶＰ,ｆｏｒｓｈｏｒｔ)ｆｏｒｆｉｒｓｔ＿ｏｒｄｅｒｉｎｔｅｇｒｏ＿ｄｉｆｆｅｒｅｎｔｉａｌｅｑｕａｔｉｏｎｏｆｍｉｘｅｄｔｙｐｅｕ′=ｆ(ｔ,ｕ,Ｔ1ｕ,Ｔ2ｕ)　　(ａ.ｅ.ｔ∈Ｉ),(1)ｕ(0)=ｕ(2π),(2)ｗｈｅｒｅＩ=[0,2π],ｆｓａｔｉｓｆｉｅｓＣａｒａｔｈｅｏｄｏｒｙ’ｓｃｏｎｄｉｔｉｏｎｓ,Ｔ1ｉｓａＶｏｌｔｅｒｒａｉｎｔｅｇｒａｌｏｐｅｒａｔｏｒ,Ｔ2ｉｓａＦｒｅｄｈｏｌｍｉｎｔｅ…     

Galois环上模拟阵的一个判别算法

Zn上的一个模拟阵可导出一个实现某存取结构的σn-理想同态密钥共享体制,本文给出Galois环上模拟阵的一个判别算法。