arXiv subjects

B. Gonul

Publications and source records attributed to B. Gonul.

14 recordsLinked to original sources

arXiv2016

Landau theory of nuclear level density and its application in description of nuclear level density in the region of discrete and s-wave neutron resonance energies

In this work, the reliability of the Landau expression for the nuclear level density calculations is tested, for the first-time, to describe nuclear level densities of some light, intermediate mass and heavy nuclei at excitations corresponding to discrete and s-wave neutron resonance energies. The chi-2 minimizing method is used in treatment of the experimental data for the two suggested energy range of discrete energies given by Nuclear Data Sheet [1] and by the systematic for nuclear level density parametrization in [2]. Our comparison with the related data in the discrete energy range has shown that the results obtained by the Landau expression are better than those of back-shifted Fermi-gas model and constant temperature approximation. This result is also valid for some nuclei of interest when the s-wave neutron resonance level density is included to check theoretical prescriptions in the energy range from initial bound states to unbound states near the neutron binding energy.

nucl-th↗

arXiv2015

Analytical solutions for the Bohr Hamiltonian with the Woods-Saxon potential

Approximate analytical solutions in closed form are obtained for the 5-dimensional Bohr Hamiltonian with the Woods-Saxon potential, taking advantage of the Pekeris approximation and the exactly soluble one-dimensional extended Woods-Saxon potential with a dip near its surface. Comparison to the data for several gamma-unstable and prolate deformed nuclei indicates that the potential can describe well the ground state and gamma-1 bands of many prolate deformed nuclei corresponding to large enough "well size" and diffuseness, while it fails in describing the beta-1 bands, due to its lack of a hard core, as well as in describing gamma-unstable nuclei, because of the small "well size" and diffuseness they exhibit.

nucl-th↗

arXiv2011

An extended scenario for the Schrodinger equation

The concept of the elegant work introduced by Levai in Ref. [5] is extended for the solutions of the Schrodinger equation with more realistic other potentials used in different disciplines of physics. The connection between the present model and the other alternative algebraic technique in the literature is discussed

math-ph↗

arXiv2006

A note on the Woods-Saxon potential

The wave Schrodinger and, to clarify one interesting point encountered in the calculations, Klein-Gordon equations are solved exactly for a single neutron moving in a central Woods-Saxon plus an additional potential that provides a flexibility to construct the surface structure of the related nucleus. The physics behind the solutions and the reliability of the results obtained are discussed carefully with the consideration of other related works in the literature. In addition, the exhaustive analysis of the results reveals the fact that the usual Woods-Saxon potential cannot be solved analytically within the framework of non-relativistic physics, unlike its exactly solvable relativistic consideration.

nucl-th↗

arXiv2006

Comparison of the Band Alignment of Strained and Strain-Compensated Gainnas QWS on Gaas and Inp Substrates

We present a comparison of the band alignment of the Ga1-xInxNyAs1-y active layers on GaAs and InP substrates in the case of conventionally strained and strained-compensated quantum wells. Our calculated results present that the band alignment of the tensiley strained Ga1-xInxNyAs1-y quantum wells on InP substrates is better than than that of the compressively strained Ga1-xInxNyAs1-y quantum wells on GaAs substrates and both substrates provide deeper conduction wells. Therefore, tensiley strained Ga1-xInxNyAs1-y quantum wells with In concentrations of x<=0.53 on InP substrates can be used safely from the band alignment point of view when TM polarisation is required. Our calculated results also confirm that strain compensation can be used to balance the strain in the well material and it improve especially the band alignment of dilute nitride Ga1-xInxNyAs1-y active layers on GaAs substrates. Our calculations enlighten the intrinsic superiority of N-based lasers and offer the conventionally strained and strain-compensated Ga1-xInxNyAs1-y laser system on GaAs and InP substrates as ideal candidates for high temperature operation.

cond-mat.mtrl-sci↗

arXiv2006

A search on the Nikiforov-Uvarov formalism

An alternative treatment is proposed for the calculations carried out within the frame of Nikiforov-Uvarov method, which removes a drawback in the original theory and by pass some difficulties in solving the Schrodinger equation. The present procedure is illustrated with the example of orthogonal polynomials. The relativistic extension of the formalism is discussed.

quant-ph↗

arXiv2006

A search on the Klein-Gordon equation

The s-wave Klein-Gordon equation for the bound states is separated in two parts to see clearly the relativistic contributions to the solution in the non-relativistic limit. The reliability of the model is discussed with the specifically chosen two examples.

quant-ph↗

arXiv2005

Equivalence of two alternative approaches to Schrodinger equations

Recently developed simple approach for the exact/approximate solution of Schrodinger equations with constant/position-dependent mass, in which the potential is considered as in the perturbation theory, is shown to be equivalent to the one leading to the construction of exactly solvable potentials via the solution of second-order differential equations in terms of known special functions. The formalism in the former solves difficulties encountered in the latter in revealing the corrections explicitly to the unperturbed piece of the solutions whereas the other obviate cumbersome procedures used in the calculations of the former.

quant-ph↗

arXiv2005

Explicit Solutions for N-Dimensional Schrodinger Equations with Position-Dependent Mass

With the consideration of spherical symmetry for the potential and mass function, one-dimensional solutions of non-relativistic Schrodinger equations with spatially varying effective mass are successfully extended to arbitrary dimensions within the frame of recently developed elegant non-perturbative technique, where the BenDaniel-Duke effective Hamiltonian in one-dimension is assumed like the unperturbed piece, leading to well-known solutions, whereas the modification term due to possible use of other effective Hamiltonians in one-dimension and, together with, the corrections coming from the treatments in higher dimensions are considered as an additional term like the perturbation. Application of the model and its generalization for the completeness are discussed.

quant-ph↗

arXiv2005

Remarks on exact solvability of quantum systems with spatially varying effective mass

Within the frame of a novel treatment we make a complete mathematical analysis of exactly solvable one-dimensional quantum systems with non-constant mass, involving their ordering ambiguities. This work extends the results recently reported in the literature and clarifies the relation between physically acceptable effective mass Hamiltonians.

quant-ph↗

arXiv2005

An Alternative Treatment for Yukawa-Type Potentials

We propose a new approximation scheme to obtain analytic expressions for the bound state energies and eigenfunctions of Yukawa like potentials. The predicted energies are in excellent agreement with the accurate numerical values reported in the literature.

quant-ph↗

arXiv2005

A New Algebraic Approach to Perturbation Theory

An algebraic non-perturbative approach is proposed for the analytical treatment of Schrödinger equations with a potential that can be expressed in terms of an exactly solvable piece with an additional potential. Avoiding disadvantages of standard approaches, new handy recursion formulae with the same simple form both for ground and excited states have been obtained. As an illustration the procedure, well adapted to the use of computer algebra, is successfully applied to quartic anharmonic oscillators by means of very simple algebraic manipulations. The trend of the exact values of the energies is rather well reproduced for a large range of values of the coupling constant (g=0.001-10000).

quant-ph↗

arXiv2005

An Approach To Potential Scattering

Recently developed time-independent bound-state perturbation theory is extended to treat the scattering domain. The changes in the partial wave phase shifts are derived explicitly and the results are compared with those of other methods.

nucl-th↗

arXiv2002

Supersymmetry and the relationship between a class of singular potentials in arbitrary dimensions

The eigenvalues of the potentials $V_{1}(r)=\frac{A_{1}}{r}+\frac{A_{2}}{r^{2}}+\frac{A_{3}}{r^{3}}+\frac{A_{4 }}{r^{4}}$ and $V_{2}(r)=B_{1}r^{2}+\frac{B_{2}}{r^{2}}+\frac{B_{3}}{r^{4}}+\frac{B_{4}}{r^ {6}}$, and of the special cases of these potentials such as the Kratzer and Goldman-Krivchenkov potentials, are obtained in N-dimensional space. The explicit dependence of these potentials in higher-dimensional space is discussed, which have not been previously covered.

quant-ph↗