Complexity and neutron star structure

We apply the statistical measure of complexity introduced by López-Ruiz, Mancini and Calbet (1995) [1] to neutron star structure. We continue the recent application of Sañudo and Pacheco (2009) [2] to white dwarfs. The interplay of gravity, the short-range nuclear force and the very short-range weak interaction shows that neutron stars, under the current theoretical framework, are ordered (low complexity) systems.     

Nature of the electronic states in a chain of potential wells in presence of an electric field

A Kronig-Penney model with a constant electric field is used to study the transmission properties of a non-interacting electron one-dimensional (1D) ordered and disordered systems with uniformly distributed negative strengths of δ-function potentials (wells). In ordered systems we examine the origin of the jumps of the transmission coefficient and the short-range localization (occurring before the first jump) observed previously. For disordered wells, we also examine the phase-diagram in the energy-disorder plane. The short-range localization is observed as a peak in the inverse participation ratio and as a minimum in the localization length. We found that the two distinctive behaviours correspond to a negative differential resistance and to a resonance at particular points corresponding to the edges of the Brillouin zones. Further discussions of these behaviours are included.     

Nature of the electronic states in a chain of potential wells in presence of an electric field

A Kronig-Penney model with a constant electric field is used to study the transmission properties of a non-interacting electron one-dimensional (1D) ordered and disordered systems with uniformly distributed negative strengths of δ-function potentials (wells). In ordered systems we examine the origin of the jumps of the transmission coefficient and the short-range localization (occurring before the first jump) observed previously. For disordered wells, we also examine the phase-diagram in the energy-disorder plane. The short-range localization is observed as a peak in the inverse participation ratio and as a minimum in the localization length. We found that the two distinctive behaviours correspond to a negative differential resistance and to a resonance at particular points corresponding to the edges of the Brillouin zones. Further discussions of these behaviours are included.     

Exchange–correlation potentials and local energies per particle along nonlinear adiabatic connections

We study nonlinear adiabatic connection paths in density-functional theory using modified electron–electron interactions that perform a long-range/short-range separation of the Coulomb interaction. These adiabatic connections allow us to define short-range exchange–correlation potentials and short-range local exchange–correlation energies per particle which we have calculated accurately for the He and Be atoms and compared to the corresponding quantities in the local density approximation (LDA). The results confirm that the LDA better describes exchange–correlation potentials and local exchange–correlation energies per particle when the range of the interaction is reduced.     

Brownian particles with long- and short-range interactions

We develop the kinetic theory of Brownian particles with long- and short-range interactions. Since the particles are in contact with a thermal bath fixing the temperature T, they are described by the canonical ensemble. We consider both overdamped and inertial models. In the overdamped limit, the evolution of the spatial density is governed by the generalized mean field Smoluchowski equation including a mean field potential due to long-range interactions and a generically nonlinear barotropic pressure due to short-range interactions. This equation describes various physical systems such as self-gravitating Brownian particles (Smoluchowski-Poisson system), bacterial populations experiencing chemotaxis (Keller-Segel model) and colloidal particles with capillary interactions. We also take into account the inertia of the particles and derive corresponding kinetic and hydrodynamic equations generalizing the usual Kramers, Jeans, Euler and Cattaneo equations. For each model, we provide the corresponding form of free energy and establish the H-theorem and the virial theorem. Finally, we show that the same hydrodynamic equations are obtained in the context of nonlinear mean field Fokker-Planck equations associated with generalized thermodynamics. However, in that case, the nonlinear pressure is due to the bias in the transition probabilities from one state to the other leading to non-Boltzmannian distributions while in the former case the distribution is Boltzmannian but the nonlinear pressure arises from the two-body correlation function induced by the short-range potential of interaction. As a whole, our paper develops connections between the topics of long-range interactions, short-range interactions, nonlinear mean field Fokker-Planck equations and generalized thermodynamics. It also justifies from a kinetic theory based on microscopic processes, the basic equations that were introduced phenomenologically to describe self-gravitating Brownian particles, chemotaxis and colloidal suspensions with attractive interactions.     

Characteristics of the conductive polyimide film surfaces induced by ultraviolet laser beam

-1 cm^-1 stripped in a solvent from KrF-laser-irradiated polyimide thin film is taken as a sample to determine the microstructure of the conducting layer. Fourier-transform infrared and X-ray photoelectron spectroscopies show the formation of the carbon-rich clusters after irradiation. The element analysis gives the atomic ratio of C:H:N:O for the carbon-rich cluster as 60:20:3:1. Wide-angle X-ray diffraction indicates that the conducting layer is mainly amorphous carbon with a small amount of the short-range ordered carbon-rich clusters. This study suggests a structural model with three-layer carbon sheets linked together in a random fashion for the short-range ordered carbon-rich clusters. The interplanar spacing is 3.87 Å and the layer diameter 25 Å. The transport model of variable-range hopping in three dimensions is used to explain the conducting behavior of the conducting layer. In our case, the short-range ordered carbon-rich clusters are assumed to be conducting islands dispersed in the amorphous carbon-rich cluster matrix. Received: 26 May 1997/Accepted: 8 September 1997     

二维合金系统的有序动力学研究

采用主方程方法在对概率近似下对三元fcc结构晶体在(001)方向的一个层面的有序无序动力学过程进行了研究.计算了长程序参量(LRO)和短程序参量(SRO)随时间的演化过程.在系统从完全无序态弛豫到平衡态的过程中存在各种瞬态有序相.瞬态相有着不同的特点,如序参量(LRO,SRO)瞬态相曲线形状不同等.产生它们的原因有不同的原子特征迁移时间、原子间最近邻和次近邻相互作用差异、短程相关性和长程相关性的差异对弛豫过程的影响. 关键词： 对概率近似 瞬态有序相 长程序参量(LRO) 长程相关性     

功率控制的强非局域空间光孤子短程相互作用

研究了功率控制的强非局域空间光孤子短程相互作用.由动量守恒,两个孤子短程相互作用时,孤子的质心轨迹因相位差而发生偏转.实验上证实了偏转幅度与功率比有关,当功率相等时,偏转最大.利用功率对相互作用的调控的特性,测量了液晶分子对光场的响应时间,发现比其对偏置电压的响应时间短很多.     

Photoemission signatures of valence-bond stripes in cuprates: Long-range vs. short-range order

Recent experiments indicate that the tendency toward the formation of unidirectional charge density waves (“stripes”) is common to various underdoped cuprates. We discuss momentum-resolved spectral properties of valence-bond stripes, comparing the situations of ideal and short-range stripe order, the latter being relevant for weak and/or disorder-pinned stripes. We find clear signatures of ordered stripes, although matrix element effects suppress most shadow band features. With decreasing stripe correlation length, stripe signatures are quickly washed out, the only remaining effect being a broadening of antinodal quasiparticles. This insensitivity of photoemission to short-range stripe order may be employed to distinguish it from nematic order, e.g. in underdoped YBa₂Cu₃O_6+δ.     

New form for the Coulomb potential in ordering alloys

A method of constructing the Coulomb potential in substitutional alloys with arbitrary positions of atoms of different species in the crystal lattice sites is suggested. The electron density distribution in the crystal is written as the sum of spherical distributions of electrons in the free atom. The work is carried out for longrange ordered alloys, though it can be easily generalized to short-range ordered alloys.     

Staggered flux state and charge order in a 2-leg triangular ladder system

Based on the t-J-V model, the possibility of the staggered flux(SF) state in a 2-leg triangular ladder system at 1/4 filling has been studied by investigating the staggered current-current correlations. We found that the amplitude of rung-rung staggered current correlations decays exponentially with a correlation length 2–3 lattice spacing. The short-range SF state becomes more stable when increasing V and becomes most stable in the vicinity of charge instability point of the system. Over the critical V value, the system becomes charge ordered.     

Nonlinear Squeezed States and Multiplication Rule of Nonlinear Squeezing Operators Gained via Nonlinear Coherent State Representation and IWOP Technique

Using the nonlinear coherent state representation we derive nonlinear squeezed states and the multiplication rule of nonlinear squeezing operators. We find that the symplectic matrices multiplication rule in nonlinear coherent state projection operator representation maps into the multiplication rule of successive nonlinear squeezing operators.The technique of integral within an ordered product of operators plays an essential role in deriving the multiplication rule.     

Nonlinear Squeezed States and Multiplication Rule of Nonlinear Squeezing Operators Gained via Nonlinear Coherent State Representation and IWOP Technique

Using the nonlinear coherent state representation we derive nonlinear squeezed states and the multiplication rule of nonlinear squeezing operators. We find that the symplectic matrices multiplication rule in nonlinear coherent state projection operator representation maps into the multiplication rule of successive nonlinear squeezing operators.The technique of integral within an ordered product of operators plays an essential role in deriving the multiplication rule.     

Ordering behaviors of the F.C.C. and B.C.C. phase alloys in the InMg,LiMg and AlZn systems

Expressions of the band-structure energy and the electrostatic energy characterized by the usual long-range and short-range order parameters are given to a binary alloy of simple metals with the f.c.c.-type or b.c.c.-type structure.The ordering energy and the local ordering energy are calculated for the InMg, LiMg and AlZn systems. The numerical results explain successfully the facts that the InMg system has the Ll₀-type and Ll₂-type ordered phases, each of which exists over a wide range of concentration and that the LiMg system has a local order with a negative short-range order parameter, while the AlZn system has that with the positive one. A lattice distortion in the Ll₀-type ordered structure of InMg is also discussed.     

Relaxation in Ni–Mn–Ga ferromagnetic shape memory alloys

Evidence of relaxation has been observed in ferromagnetic Ni–Mn–Ga single crystals. The relaxation may be explained by a change in symmetry-conforming short-range ordering according to Ren and Otsuka in this off-stoichimetric ordered alloy. Martensite stabilization has also been found after martensite ageing.     

Nonlinearity in cooperative systems-dynamical Bethe-Ising model

The dynamics of the short-range order as well as the long-range order in the nonlinear cooperative system is investigated specifically for a kinetic Ising model in the Bethe approximation. The phenomena of critical slowing down near the transition temperatureT _c and anomalous fluctuation belowT _c are directly related to the instability of the long-range order. The dynamics of the short-range order is essentially a fast mode and is noncritical. However, through the nonlinear coupling the short-range order is also influenced by the critical behavior of the long-range order.     

Diffraction from adsorption systems with antiphase boundaries or islands

The structure function for overlayer systems containing either antiphase islands or domains is considered. It is shown using statistical arguments that a central notch in the superlattice beam predicted in previous papers does not exist. The use of LEED in determining order and some parodoxical effects of the LEED instrument response function on diffraction patterns from long- and short-range ordered systems are discussed.     

Two-dimensional melting far from equilibrium in a granular monolayer

We report an experimental investigation of the transition from a hexagonally ordered solid phase to a disordered liquid in a monolayer of vibrated spheres. The transition occurs as the intensity of the vibration amplitude is increased. Measurements of the density of dislocations and the positional and orientational correlation functions show evidence for a dislocation-mediated continuous transition from a solid phase with long-range order to a liquid with only short-range order. The results show a strong similarity to simulations of melting of hard disks in equilibrium, despite the fact that the granular monolayer is far from equilibrium due to the effects of interparticle dissipation and the vibrational forcing.     

Spectrum of the short-range order parameters [in ordered alloys] as a function of electron concentration using the approximation of long-range oscillatory interactions

The values of the short-range ordering parameters [in ordered alloys] are calculated on the assumption that the spectrum of the ordering energies is specified by way of the approximation of almost-free electrons, screened on the Hartree principle. It is found that on rising this approximation for the ordering energies the signs of the short-range order parameters in the first, second, and third coordination spheres are determined by the signs of the ordering energies in the corresponding spheres.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 117–123, January, 1976.The authors wish to thank Professor V. I. Iveronova for discussing the results of the present investigation.