On the effects on a Landau-type system for an atom with no permanent electric dipole moment due to a Coulomb-type potential

We analyse the bound states for a Landau-type system for an atom with no permanent electric dipole moment subject to a Coulomb-type potential. By comparing the energy levels for bound states of the system with the Landau quantization for an atom with no permanent electric dipole moment (Furtado et al., 2006), we show that the energy levels of the Landau-type system are modified, where the degeneracy of the energy levels is broken. Another quantum effect investigated is a dependence of the angular frequency of the system on the quantum numbers associated with the radial modes and the angular momentum. As examples, we obtain the angular frequency and the energy levels associated with the ground state and the first excited state of the system.     

Zitterbewegung in Quantum Mechanics

The possibility that zitterbewegung opens a window to particle substructure in quantum mechanics is explored by constructing a particle model with structural features inherent in the Dirac equation. This paper develops a self-contained dynamical model of the electron as a lightlike particle with helical zitterbewegung and electromagnetic interactions. The model admits periodic solutions with quantized energy, and the correct magnetic moment is generated by charge circulation. It attributes to the electron an electric dipole moment rotating with ultrahigh frequency, and the possibility of observing this directly as a resonance in electron channeling is analyzed in detail. Correspondence with the Dirac equation is discussed. A modification of the Dirac equation is suggested to incorporate the rotating dipole moment.     

基于几何遮蔽效应和法拉第旋光效应耦合的磁流体偏振光透过率

根据几何遮蔽效应和法拉第旋光效应耦合原理给出的解析表达式,通过数值模拟计算,研究了磁流体的纵场诱导偏振光透过率及磁流体的浓度、液态介电常量、磁性颗粒磁偶极矩热能比和单位磁性颗粒团聚体所含磁性颗粒数量四个参量的变化对其偏振光透过率的影响.结果表明,磁流体的浓度、液态介电常量和磁性颗粒磁偶极矩热能比对其偏振光透过率有显著影响,低浓度样品的偏振光透过率随着纵向磁场强度的增大而线性增加,而高浓度样品则随着纵向磁场强度的增大呈现振荡变化的特性.在一定范围内,磁流体偏振光透过率随其液态介电常量εliquid和磁性颗粒磁偶极矩热能比μd/(kT)的变大而增加.而单位磁性颗粒团聚体所含磁性颗粒数量对其偏振光透过率没有影响,磁流体参量依赖的偏振光透过率在低磁场区域和高磁场区域有明显区别.提出了磁流体纵场诱导偏振光透过率在几类光子器件中的可能应用.     

基于几何遮蔽效应和法拉第旋光效应耦合的磁流体偏振光透过率

根据几何遮蔽效应和法拉第旋光效应耦合原理给出的解析表达式,通过数值模拟计算,研究了磁流体的纵场诱导偏振光透过率及磁流体的浓度、液态介电常量、磁性颗粒磁偶极矩热能比和单位磁性颗粒团聚体所含磁性颗粒数量四个参量的变化对其偏振光透过率的影响.结果表明,磁流体的浓度、液态介电常量和磁性颗粒磁偶极矩热能比对其偏振光透过率有显著影响,低浓度样品的偏振光透过率随着纵向磁场强度的增大而线性增加,而高浓度样品则随着纵向磁场强度的增大呈现振荡变化的特性.在一定范围内,磁流体偏振光透过率随其液态介电常量ε_liquid和磁性颗粒磁偶极矩热能比μ_d/(kT)的变大而增加.而单位磁性颗粒团聚体所含磁性颗粒数量对其偏振光透过率没有影响,磁流体参量依赖的偏振光透过率在低磁场区域和高磁场区域有明显区别.提出了磁流体纵场诱导偏振光透过率在几类光子器件中的可能应用.     

外电场下GaN的特性研究

以6-311G(3df,3pd)为基组,采用B3PW91方法优化得到GaN基态分子的几何结构,并探究了电场对GaN分子基态能量、电荷布居数、键长、偶极矩、振动频率、红外光谱强度、HOMO、LUMO能级影响.研究表明:无电场时,谐振频率值为576.2218 cm~(-1),与实验值484.9 cm~(-1)很接近.有电场时,键长、偶极矩、能隙Eg、电荷布居数、红外谱强度、HOMO和LUMO能级随电场的增大而减小;谐振频率和分子总能量随电场的增加而增加.谐振频率和红外谱强度对电场有着明显的依赖关系,这对材料的光学特性研究有提供理论参考.     

Electro-optics of molecules

The natural vibrations and electro-optics of diatomic molecules are considered in the framework of the perturbation theory. The energy of anharmonic vibrations and the matrix of a dipole moment function are determined with allowance made only for nonzero perturbation contributions. In particular, the case of strong electro-optical anharmonicity of diatomic molecules (i.e., the situation where the dipole moment function significantly deviates from linear behavior) is analyzed in the second order of the perturbation theory. Within the introduced formalism of polynomials of the quantum numbers, the perturbation theory is extended to polyatomic molecules and expressions for the matrix elements of the dipole moment are derived in explicit form with due regard for the vibrational quantum numbers.     

外电场下TCNQ的激发与光谱性质研究

采用密度泛函B3PLY方法优化了不同外电场下TCNQ分子的基态稳定构型、电偶极矩和分子的总能量,并且分析了TCNQ分子的HOMO-2到LUMO+2轨道的能量变化。然后利用杂化CIS-DFT方法在同样的基组下计算了外电场下TCNQ分子的前9个激发态的激发能、波长和振子强度,结果表明在没有外电场的情况下,TCNQ分子只有一个激发态能够激发,从基态跃迁到第1激发态。在有外电场的作用下,总能量随外电场的增加而逐渐减少,偶极矩随外电场的增加而不断增加。其前线轨道的能量也随外电场的增加不断减少,轨道分布也受外电场很大的影响。另外,外电场对TCNQ分子的激发波长也产生了一定影响。     

外电场下TCNQ的激发与光谱性质研究

采用密度泛函B3PLY方法优化了不同外电场下TCNQ分子的基态稳定构型、电偶极矩和分子的总能量，并且分析了TCNQ分子的HOMO-2到LUMO+2轨道的能量变化。然后利用杂化CIS-DFT方法在同样的基组下计算了外电场下TCNQ分子的前9个激发态的激发能、波长和振子强度，结果表明在没有外电场的情况下，TCNQ分子只有一个激发态能够激发，从基态跃迁到第1激发态。在有外电场的作用下，总能量随外电场的增加而逐渐减少，偶极矩随外电场的增加而不断增加。其前线轨道的能量也随外电场的增加不断减少，轨道分布也受外电场很大的影响。另外，外电场对TCNQ分子的激发波长也产生了一定影响。     

Double ionization of helium studied with the multi-configuration time-dependent Hartree–Fock method

The intensity dependence of double ionization probability of helium in a strong laser field is investigated by using the multi-configuration time-dependent Hartree–Fock (MCTDHF) method. The results agree with the previous theoretical report by directly solving the time-dependent Schrödinger equation. The time evolution of electronic population on the ground state, electronic energy and dipole moment are also presented and discussed.     

Observation of a turbulence-induced large scale magnetic field

An axisymmetric magnetic field is applied to a spherical, turbulent flow of liquid sodium. An induced magnetic dipole moment is measured which cannot be generated by the interaction of the axisymmetric mean flow with the applied field, indicating the presence of a turbulent electromotive force. It is shown that the induced dipole moment should vanish for any axisymmetric laminar flow. Also observed is the production of toroidal magnetic field from applied poloidal magnetic field (the omega effect). Its potential role in the production of the induced dipole is discussed.     

Semiempirical law for the dipole moments of low-molecular-weight gelators

Some small chiral organic molecules are capable of forming gel in low-concentration solutions. This phenomenon is of great theoretical interest, but its molecular details are still unclear. High chemical diversity of such gelators impedes the investigation of their common structural properties important for gel formation. Here, we calculated the total dipole moment for a set of gelators with sufficiently different chemical structures by means of molecular dynamics simulations. It was found that all considered molecules have a dipole moment of ～3 D or more. This means that the energy of the dipole-dipole interaction between two point dipoles at a distance of 6–8 Å is ～kT. This distance roughly corresponds to molecules in close contact. This makes it possible to conclude that the dipole moment can orient gelator molecules before aggregation, thereby playing a key role in the process of gelation. This orientation effect determines the anisotropy of aggregates and the gelation of the solution.     

Electric-field induced dipole blockade with Rydberg atoms

High resolution laser Stark excitation of np (60相似文献   

Flexoelectric effect modelling

A statistical theory of dipole flexoelectric (FE) polarization in liquid crystals is used to calculate temperature dependence of order parameters, elastic constants and FE coefficients. Two systems with polar wedge-shaped and banana-shaped molecules are investigated. In both cases, the FE coefficients are proportional to the dipole moment component parallel to the molecule symmetry axis. It results from the symmetries of interactions and of the Mayer function. The origin of the FE effect and microscopic pictures of the distorted phases are discussed.     

Photoselection of impurity molecules with respect to the orientation of their stark moments induced by an amorphous matrix

A method of selective (relative to the magnitude of the linear Stark effect in zero-dipole impurity molecules) burning of holes in the spectra of amorphous matrices is studied. It is shown that this method makes it possible not only to select a subensemble of impurity molecules having both preset energy of the 0-0 transition and magnitude of the matrix-induced Stark moment, but also to divide this subensemble into two fractions whose Stark moments are predominantly oriented either along the transition moment or perpendicular to it. The possibility of experimental verification of the most popular hypothesis about the origin of induced Stark moments, which neglects a possible correlation between the direction of the Stark moment and that of the transition dipole moment, is considered. The method described also allows one to study experimentally the correlation of some other photophysical parameters of impurity molecules with the direction of local internal fields relative to the vector of the transition dipole moment.     

H2O分子在不同电荷态的重离子作用下的离化

利用含时密度泛函理论和局域密度近似方法，计算了H2O分子在速度为12．5α0／fs的重离子C^＋和C^2＋作用下产生的各种电荷态的H2O分子离子的几率、平均逃逸电子数和偶极矩的变化随时间的演化。计算结果表明，在重离子势最大时，电偶极矩的变化最大，重离子的电荷态越高，得到高电荷态H2O分子的几率越大；重离子远离分子时，电偶极矩的变化趋于平缓。The time-dependent density functional theory （TDDFT） and local density approximation （LDA） are used to calculate the dipole moment changes, the ionization probabilities of the H20 molecule and the time-dependent probabilities of escaped electrons in the process of excitation of H2O molecule by C^＋ , C^2＋ with energy of 2.3 MeV/u. It is shown that the dipole moment changes of H2O are the greatest and the higher the charge staate of heavy ion, the bigger the probabilities of the high charge state of H2O molecule at maximal heavy ion potential. The dipole moment changes slightly when heavy ion leaved far from molecule.     

Quantized Magnetic Flux in the Bohr–Sommerfeld Model

Based on the Bohr–Sommerfeld model, we investigate the quantization of magnetic flux through the electronic orbits together with its dependence on additional sources of magnetic fields. The additional magnetic field causes changes of the angular momentum and hence shifts of the energy of the atomic levels. We study this effect for the cases of the Zeeman effect, where the source is an external homogeneous magnetic field, and the hyperfine interaction, where the source is the field of the magnetic moment of the nucleus. We discuss a model for the handling of the different angular momentum contributions for which the energy shifts due to the Zeeman effect and the magnetic dipole contribution to the hyperfine interaction can be reproduced quite well. The meaning of “spin,” however, changes within this approach drastically. The unusual Landé g-factor of the electron is discussed to be the result of a reduced ground-state angular momentum of the electron in combination with the field of the magnetic moment of the electron rather than an intrinsic property of the electron.     

Magnetic force signal of vortex creation in type-II superconducting thin films

The possibility of the formation of a vortex in thin film due to the field of magnetic dipole moment when a point dipole is vertically approaching the surface of a thin film is discussed. Calculations are performed for certain discrete values of the critical position of the point dipole for creating the vortex in the thin film and the equilibrium positions of the vortex, both of which depend on the strength of magnetic dipole moment. The creation of a new single vortex in the thin film causes an abrupt change in the vertical force.     

Three-dimensional ab initio dipole moment surfaces and stretching vibrational band intensities of the XH3 molecules

Stretching vibrational band intensities of XH₃ (X=N, Sb) molecules are investigated employing three-dimensional dipole moment surfaces combined with the local mode Hamiltonian model.The dipole moment surfaces of NH₃ and SbH₃ are calculated with the density functional theory and at the correlated MP2 level,respectively. The calculated band intensities are in good agreement with the available experimental data. The contribution to the band intensities from the different terms in the polynomial expansion of the dipole moments of four group V hydrides (NH₃, PH₃,AsH₃ and SbH₃) are discussed. It is concluded that the breakdown of the bond dipole approximation must be considered. The intensity “borrowing” effect due to the wave function mixing among the stretching vibrational states is found to be less significant for the molecules that reach the local mode limit.     

The search for a potentially new molecular species,SiAs: A theoretical contribution

Electronic states of a new molecular species, SiAs, correlating with the three lowest dissociation channels are characterized at a high-level of theory using the CASSCF/MRCI approach along with quintuple-ξ quality basis sets. This characterization includes potential energy curves, vibrational energy levels, spectroscopic parameters, dipole and transition dipole moment functions, transition probabilities, and radiative lifetimes. For the ground state (X²Π), an assessment of spin–orbit effects and the interaction with the close-lying A²Σ⁺ state is also reported. Similarities and differences with other isovalent species such as SiP and CAs are also discussed.     

Stark Hole-Burning Spectroscopy of Cresylviolet Perchlorate in Amorphous Hosts

Stark hole-burning spectroscopy is used to investigate the effective dipole moment change of cresylviolet perchlorate (CVP) in various glass and polymer hosts such as ethanol:methanol (EM), polyvinyl alcohol (PVA), poly (2-hydroxyethyl) methacrylate (PHEMA), polyvinylbutyral (PVB), and formamide. The strong correlation between effective dipole moment change of the guest molecule and the holeburning efficiencies of the host matrices illustrates the sensitivity of the dipole moment change as a direct measure of guest-host interactions. Hole-burning is found to be more efficient as the dipole induced reaction field increases. This relationship is discussed in terms of the unusual hole-burning mechanism suggested for this molecule. The effective dipole moment change of cresylviolet perchlorate ranges from 0.14 to 0.59 Debye.