International Journal of Modern Physics B

A philosophically consistent axiomatic approach to classical and quantum mechanics is given. The approach realizes a strong formal implementation of Bohr's correspondence principle. In all instances, classical and quantum concepts are fully parallel: the same general theory has a classical realization and a quantum realization. Extending the ''probability via expectation'' approach of Whittle to noncommuting quantities, this paper defines quantities, ensembles, and experiments as mathematical concepts and shows how to model complementarity, uncertainty, probability, nonlocality and dynamics in these terms. The approach carries no connotation of unlimited repeatability; hence it can be applied to unique systems such as the universe. Consistent experiments provide an elegant solution to the reality problem, confirming the insistence of the orthodox Copenhagen interpretation on that there is nothing but ensembles, while avoiding its elusive reality picture. The weak law of large numbers explains the emergence of classical properties for macroscopic systems.

In this communication we introduce a pair of coupled continuum equations to model overlayer growth with evaporation-accretion due to thermal or mechanical agitations of the substrate. We gain insight into the dynamics of growth via one-loop perturbative techniques. This allows us to analyze our numerical data. We conclude that there is a crossover behaviour from a roughening regime to a very long-time, large length scale smoothening regime.

Temperature dependence of the upper critical field H_c2(T), lower critical field H_c1(T) and thermodynamic magnetic field H_cm(T) are studied in the vicinity of T_c using a two-band Ginzburg–Landau (GL) theory. The results are shown to be in a good agreement with experimental data for the superconducting magnesium diboride (MgB₂) and non-magnetic borocarbides LuNi₂B₂C(YNi₂B₂C). In addition, two-band GL theory was applied for the calculation of specific heat jump, which is smaller than in single-band GL theory. Peculiarities of Little–Parks effect in two-band GL theory are studied also. It is shown that the quantization of the magnetic flux and the relation between surface magnetic field H_c3(T) and upper critical field H_c2(T) are the same as in single band GL theory.

We find analytically the conditions to form a nearly helical conformation for a model of double-stranded DNA under external force and torque. For such conformations, the tilting angle can be either oscillatory or decaying with increasing arclength, depending on the relationship among the force, torque and initial tilting angle. Both conformations are possible for a small initial tilting angle while only the oscillatory solution is possible for a large initial tilting angle. Phase diagram that depicts the oscillatory and decaying solutions is calculated. The corresponding linking number, twist, writhe number, relative extension and the locus of the chain are also calculated analytically.

The electron paramagnetic resonance and optical absorption spectra of VO²⁺ ions in different alkali barium phosphate glasses have been studied and the results have been analysed using C_4v symmetry. The EPR spectrum shows eight hyperfine lines characteristic of VO²⁺ ions. From the observed EPR spectra, the spin-Hamiltonian parameters, Fermi contact interaction parameter k, dipolar hyperfine coupling parameter P have been evaluated. The EPR spectra exhibit a marked concentration dependence. The EPR spectra were also recorded at different temperatures. The number of spins participating in resonance is found to be increasing with decreasing temperature. The paramagnetic susceptibility χ is calculated from the EPR data. As the temperature decreases, χ increases in accordance with Curie's law. The optical absorption spectrum exhibits two bands corresponding to the transitions ²B_2g → ²B_1g and ²B_2g → ²E_g, characteristic of VO²⁺ ions in octahedral symmetry with tetragonal distortion. From the ultraviolet edges of these optical absorption spectra, the optical band gap energies (E_opt) of the glass samples have been calculated. The optical band gap energy varies with alkali content. By correlating EPR and optical absorption data, the molecular orbital coefficients have been evaluated. The theoretical values of optical basicity of the glasses have also been evaluated.

Glasses of the xFe₂O₃·(100-x) [3B₂O₃·KCl] system, with 0 < x ≤ 20 mol%, were investigated by means of EPR and magnetic susceptibility measurements. The Fe³⁺ ions in sites of distorted octahedral symmetry and clustered formations containing both Fe³⁺ and Fe²⁺ ionic species were verified. Dipolar and super-exchange interactions involving iron ions were revealed depending on the iron content of the sample.

Molecular dynamical simulation has been carried out to investigate the structure and dynamics of a dipolar fluid under strong shear. The dipolar fluid consists of polizable particles, which have an induced dipole moment in the applied field direction. The shear stress is perpendicular to the field direction. When the shear stress is small, the flow has a flowing-chain structure. If the shear stress increases beyond a critical value, the flowing-chain structure changes to flowing layer structure. Each layer is parallel to flow direction and the shear direction. Within one layer, the particles form strings in the flow direction.

We investigate multifractal properties for an Abelian directed model of self-organized criticality that describes the growth of droplets inside a cloud and the subsequent rainfall. The probability distribution of events of the model satisfies finite-size scaling. We obtain the singularity spectra f(α) associated with temporal records for avalanche size and for the potential energy, defined by the total sum of the product between mass and height of each site. The measure defined by avalanche size has a clear cut multifractal character, while the obtained f(α) for potential energy may include a spurious branch.