نتایج جستجو برای: Dielectric ‎Function.‎

تعداد نتایج: 1248395  

پایان نامه :دانشگاه تربیت معلم - تهران - دانشکده علوم 1393

in this thesis, structural, electronical, and optical properties of inverse pervskite(ca3pbo) in cubic phase have been investigated.the calculation have been done based on density functional theory and according to generalized gradiant approximate (gga) as correlating potential. in order to calculate the configurations, implementing in the wien2k code have been used from 2013 version. first of ...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه ارومیه 1377

the methods which are used to analyze microstrip antennas, are divited into three categories: empirical methods, semi-empirical methods and full-wave analysis. empirical and semi-empirical methods are generally based on some fundamental simplifying assumptions about quality of surface current distribution and substrate thickness. thses simplificatioms cause low accuracy in field evaluation. ful...

Journal: :journal of nanostructures 2013
s. a. hashemizadeh v. rafee

in this paper, for the first time we have studied theoretically the effect of exchange-correlation holes around electrons in gaalas/gaas/gaalas nanostructure on the temperature-dependent dynamic dielectric function of two-dimensional electron gas by employing random phase, stls and hubbard approximations. also, we have investigated another interesting system which is coupled quantum wells struc...

Despite the simplicity of the hexagonal graphene structure formed by carbon atoms, the electronic behavior shows fascinating properties, giving high expectation for the possible applications of graphene in the field. The Graphene Nano-Ribbon Field Effect Transistor (GNRFET) is an emerging technology that received much attention in recent years. In this paper, we investigate the device performan...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه شهید بهشتی - دانشکده علوم 1389

چکیده ندارد.

In this research, the optical properties of tungsten disulfide including dielectric function, the static refractive index, the imaginary part of the dielectric function, optical band gap, energy loss spectrum and its magnetic properties have been studied. Calculations have been done by using Quantum Espresso package which is based on density functional theory and pseudo-potential technique. The...

Journal: :مهندسی بیوسیستم ایران 0
محمود سلطانی فیروز کارشناسی ارشد، دانشگاه تهران رضا علیمردانی استاد، دانشگاه تهران محمود امید استاد، دانشگاه تهران

grading of agricultural products has always been a subject of research by scientists. one of the criteria to be chosen for grading of fruits is the fruit's level of ripeness. different methods have been employed to assess the status of fruit ripeness some of which are destructive and others are not so. in this research, a noninvasive capacitive method was used to estimate the ripeness leve...

The longitudinal optical conductivity is the most important property for graphene-baseddevices. So investigating this property for spatially separated few-layer graphene systems analytically and numerically is the main purpose of our study. Each layer can be mono- or bi-layer graphene. The density-density correlation function has been screened by the dielectric function using the random p...

The aim of the present study was to evaluate the properties of linear andnonlinear optics of the Schiff base Salen. Crystal structure of nanoparticles wasdetermined by a Bruker make diffractometer, Cu-K X-rays of wavelength (=1.5406Å). The XRD patterns were recorded in the 2 range of 10–90o with a step width of 0.02s-1. The UV-Vis Spectra recorded on a computerized double - beam Shimadzu 255...

In this paper, we have studied the photonic band structure of function photonic crystals in which the dielectric constant of the scattering centers (rods) is a function of space coordinates. The under-studied lattice is hexagonal and cross section of rods has a circular symmetry embedded in the air background. Photonic band structures for both electric and magnetic polarizations of the electrom...

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