Scaling behavior of a one-dimensional correlated disordered electronic System

A one-dimensional diagonal tight binding electronic system with correlated disorder is investigated. The correlation of the random potential is exponentially decaying with distance and its correlation length diverges as the concentration of "wrong sign" approaches to 1 or 0. The correlated random number sequence can be generated easily with a binary sequence similar to that of a one-dimensional spin glass system. The localization length (LL) and the integrated density of states (IDOS) for long chains are computed. A comparison with numerical results is made with the recently developed scaling technique results. The Coherent Potential Approximation (CPA) is also adopted to obtain scaling functions for both the LL and the IDOS. We confirmed that the scaling functions show a crossover near the band edge and establish their relation to the concentration. For concentrations near to 0 or 1 (longer correlation length case), the scaling behavior is followed only for a very limited range of the potential strengths.Comment: will appear in PR

Absorption Spectrum and Density of States of Square, Rectangular, and Triangular Frenkel Exciton Systems with Gaussian Diagonal Disorder

WOS: 000408446700001Using the coherent potential approximation, we investigate the effects of disorder on the optical absorption and the density of states of Frenkel exciton systems on square, rectangular, and triangular lattices with nearest-neighbor interactions and a Gaussian distribution of transition energies. The analysis is based on an elliptic integral approach that gives results over the entire spectrum. The results for the square lattice are in good agreement with the finite-array calculations of Schreiber and Toyozawa. Our findings suggest that the coherent potential approximation can be useful in interpreting the optical properties of two-dimensional systems with dominant nearest- neighbor interactions and Gaussian diagonal disorder provided the optically active states are Frenkel excitons

İnce ve eğrisel şerit yapıdaki tabaklı geometriden iki boyutlu saçınım probleminin incelenmesi

İnce ve eğrisel şerit yapıdaki tabaklı geometriden iki boyutlu saçınım probleminin incelenmesi</p

Optical Absorption of the beta-Phase of Poly(9,9-dioctylfluorene)

WOS: 000375879200001We outline a theory for the optical absorption of the beta-phase of poly(9,9-dioctylfluorene) (PFO) that is based on the Frenkel exciton model. The absorption peak at 435 nm is attributed to polymer segments having torsion angles equal to p that are weakly perturbed by the presence of random monomer junctions with torsion angles equal to 0. The broad band below 435 nm is associated with disordered segments having a broad distribution of random torsion angles. The effects of small random deviations from p in the torsion angles are discussed. The calculations support the interpretation that the b-phase is characterized by alternating segments of highly ordered and strongly disordered regions. PFO is a widely studied fluorene-based polymer with interesting and potentially useful photophysical properties. In this work, Frenkel exciton states in the beta-phase of PFO are studied, and a two-region model-weak torsional disorder and strong torsional disorder-is presented. The peak in the optical absorption at 435 nm is associated with the weakly disordered regions. The broad background in the absorption is attributed to the strongly disordered regions. (C) 2016 Wiley Periodicals, Inc

Scattering from the flat strip geometries in the layered medium by using the sinc based method of moments

Progress in Electromagnetics Research Symposium (PIERS 2008) -- JUL 02-06, 2008 -- Cambridge, MAWOS: 000259299300143In this study, we solved the electromagnetic scattering from the strip in the layered medium. The sinc type basis functions are used with their mathematical properties and GPOF technique provides us fast computation of the Green's functions in the layered medium. Therefore we obtain an algebraic matrix equation without using integration instead we used the approximated analytical forms with a specified error criteria like the few digits accuracy in the ordinary MoM.Schlumberger Doll Res, MIT Ctr Electromagnet Theory & Applicat, Res Lab Elect, Zhejiang Univ, Electromagnet Acad, Electromagnet Aca

Radiation performance of metamaterial cylindrical reflector antenna having a conic section profile illuminated by An E-polarized complex source line beam

15th International Conference on Mathematical Methods in Electromagnetic Theory (MMET) -- AUG 26-28, 2014 -- Dnipropetrovsk, UKRAINEWOS: 000364989500023Parabolic conic section profile, cylindrical metamaterial reflector antenna radiation characteristic is analyzed by using the Method of Analytical Regularization (MAR) techniques. E polarized complex source point is located at the focal point is used to illuminate the antenna. Far field radiation patterns are obtained for metamaterial and dielectric cases.IEEE AP MTT ED GRS NPS AES EMB E Ukraine Joint Chapter, O Honchar Dnipropetrovsk Natl Univ, Natl Acad Sci Ukraine, Inst Radiophys & Elect, Inst Elect & Elect Engineers, IEEE Aerosp & Elect Syst Soc, IEEE Geoscience & Remote Sensing Soc, Off Naval Res Global, TICRA Fd

Electromagnetic scattering from layered strip geometries: the method of moments study with the sinc basis

WOS: 000291757200007Electromagnetic scattering from strips of layers is analyzed using the method of moments (MoM) for both polarizations in spatial domain with the sinc-type orthogonal sets as basis and testing functions. We exploited the sine function's properties of exponential convergence, the orthogonality, easy convolution and better handling of singular kernels in MoM procedure resulting in fast performance and reasonable accuracy even in ordinary MoM treatment. We transferred the integral of the Hankel function multiplied by sinc functions to Hankel function introducing a slight error with large band width. We proved that this relative error during the generation of the main matrix elements is smaller than that of the free space error, i.e., 1%-0.5% for considerably large matrix sizes. Our approach is readily applicable to a singular kernel problem due to properties of the sinc functions in particular 2D geometry. The procedure undertaken here is proven to be very efficient as regard to similar treatments in the literature developed mainly for regular kernels. Various numerical results are calculated such as the surface induced current and normalized far field radiation pattern. We compared them with the results available in the literature

SYNTHESIS OF A Fe3O4/PAA-BASED MAGNETIC FLUID FOR FARADAY-ROTATION MEASUREMENTS

WOS: 000319783400010Highly water-soluble Fe3O4/PAA (polyacrylic acid) nanoparticles (NPs) were synthesized with the high-temperature hydrolysis method. We report the first demonstration of Faraday rotation (FR) for a magnetic fluid (MF) synthesized with this novel method. The experiments were performed in the DC regime (0-6 . 10(-2) T) at room temperature for 14 concentrations from 1.8 mg/ml to 5 mg/ml. The maximum rotation was recorded as 0.96 degrees cm(-1) for 3.33 mg/ml and this is called the critical concentration (C-CRITICAL). It was found that the rotation tends to decrease when the concentration is higher than C-CRITICAL. The MF behavior for FR is discussed with respect to substructure interactions (particle-particle, chain-chain). This work provides a new insight for the FR investigations of MFs including highly water-soluble magnetic NPs