scholarly journals Exact Solutions of a Class of Double-Well Potentials: Algebraic Bethe Ansatz

2017 ◽  
Vol 2017 ◽  
pp. 1-13 ◽  
Author(s):  
M. Baradaran ◽  
H. Panahi
Keyword(s):  
Bethe Ansatz ◽  
Numerical Evaluation ◽  
Energy Levels ◽  
Algebraic Approach ◽  
Wave Functions ◽  
Algebraic Equations ◽  
Ansatz Method ◽  
Exact Solvability ◽  
Exactly Solvable ◽  
Bistable Potential

Applying the Bethe ansatz method, we investigate the Schrödinger equation for the three quasi-exactly solvable double-well potentials, namely, the generalized Manning potential, the Razavy bistable potential, and the hyperbolic Shifman potential. General exact expressions for the energies and the associated wave functions are obtained in terms of the roots of a set of algebraic equations. Also, we solve the same problems using the Lie algebraic approach of quasi-exact solvability through the sl(2) algebraization and show that the results are the same. The numerical evaluation of the energy spectrum is reported to display explicitly the energy levels splitting.

scholarly journals Lie Symmetry and the Bethe Ansatz Solution of a New Quasi-Exactly Solvable Double-Well Potential

2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
M. Baradaran ◽  
H. Panahi
Keyword(s):  
Bethe Ansatz ◽  
Algebraic Approach ◽  
Lie Symmetry ◽  
Wave Functions ◽  
Ansatz Method ◽  
Exactly Solvable ◽  
Bethe Ansatz Solution ◽  
Double Well Potential ◽  
Potential Parameters ◽  
Good Agreement

We study the Schrödinger equation with a new quasi-exactly solvable double-well potential. Exact expressions for the energies, the corresponding wave functions, and the allowed values of the potential parameters are obtained using two different methods, the Bethe ansatz method and the Lie algebraic approach. Some numerical results are reported and it is shown that the results are in good agreement with each other and with those obtained previously via a different method.

Dirac Bound States of the Killingbeck Potential Under External Magnetic Fields

2015 ◽  
Vol 70 (7) ◽  
pp. 499-505 ◽  
Author(s):  
Zahra Sharifi ◽  
Fateme Tajic ◽  
Majid Hamzavi ◽  
Sameer M. Ikhdair
Keyword(s):  
Wave Function ◽  
Magnetic Fields ◽  
Ground State ◽  
Bound States ◽  
State Energy ◽  
Potential Model ◽  
Energy Levels ◽  
Energy Eigenvalue ◽  
Wave Functions ◽  
Ansatz Method

AbstractThe Killingbeck potential model is used to study the influence of the external magnetic and Aharanov–Bohm (AB) flux fields on the splitting of the Dirac energy levels in a 2+1 dimensions. The ground state energy eigenvalue and its corresponding two spinor components wave functions are investigated in the presence of the spin and pseudo-spin symmetric limit as well as external fields using the wave function ansatz method.

Dirac equation with CPRS potential and Cornell tensor interaction in the presence of spin and pseudospin symmetry

2020 ◽  
Vol 29 (08) ◽  
pp. 2050064
Author(s):  
Parisa Sedaghatnia ◽  
Hassan Hassanabadi ◽  
Marc de Montigny
Keyword(s):  
Dirac Equation ◽  
Nuclear Physics ◽  
Energy Levels ◽  
Pseudospin Symmetry ◽  
Tensor Interaction ◽  
Wave Functions ◽  
Nuclear Spectroscopy ◽  
Exactly Solvable

Motivated by the prominent role of tensor interactions in nuclear spectroscopy and many applications of spin and pseudospin symmetry in hadronic and nuclear physics, we solve the Dirac equation with a CPRS potential and a Cornell tensor interaction, in the spin and pseudospin symmetry limits, by using the quasi-exactly solvable method. We obtain explicitly the wave functions for the two lowest energy levels, both for spin and pseudospin symmetry. We also discuss the degeneracy of the system.

GELFAND-LEVITAN EQUATION AND QUASI-EXACT SOLVABILITY

1991 ◽  
Vol 06 (08) ◽  
pp. 739-742 ◽  
Author(s):  
A.G. USHVERIDZE
Keyword(s):  
Energy Levels ◽  
Exactly Solvable Models ◽  
Solvable Models ◽  
Exact Solvability ◽  
Exactly Solvable

It is shown that following the Gelfand-Levitan approach and starting from L-parameter class of 1-dimensional quasi-exactly solvable models with M+1 explicitly calculable energy levels one can obtain a new (L+M+1)-parameter class of quasi-exactly solvable models with the same M+1 energy levels.

scholarly journals QUASI-EXACTLY SOLVABLE DEFORMATIONS OF GAUDIN MODELS AND "QUASI-GAUDIN ALGEBRAS"

1998 ◽  
Vol 13 (04) ◽  
pp. 281-292 ◽  
Author(s):  
A. G. USHVERIDZE
Keyword(s):  
Bethe Ansatz ◽  
Complete Integrability ◽  
Integrable Models ◽  
Exact Solvability ◽  
New Class ◽  
Algebraic Bethe Ansatz ◽  
Exactly Solvable ◽  
Algebraic Deformation ◽  
Bethe Ansatz Solution ◽  
Gaudin Models

A new class of completely integrable models is constructed. These models are deformations of the famous integrable and exactly solvable Gaudin models. In contrast with the latter, they are quasi-exactly solvable, i.e. admit the algebraic Bethe ansatz solution only for some limited parts of the spectrum. An underlying algebra responsible for both the phenomena of complete integrability and quasi-exact solvability is constructed. We call it "quasi-Gaudin algebra" and demonstrate that it is a special non-Lie-algebraic deformation of the ordinary Gaudin algebra.

scholarly journals QUASI-EXACTLY SOLVABLE SCHRÖDINGER EQUATIONS, SYMMETRIC POLYNOMIALS AND FUNCTIONAL BETHE ANSATZ METHOD

2018 ◽  
Vol 58 (2) ◽  
pp. 118 ◽  
Author(s):  
Christiane Quesne
Keyword(s):  
Bethe Ansatz ◽  
Linear Equations ◽  
Polynomial Solution ◽  
Schrodinger Equations ◽  
Schrödinger Equations ◽  
Symmetric Polynomials ◽  
Ansatz Method ◽  
Exactly Solvable ◽  
Solvable Extension ◽  
Elementary Symmetric Polynomials

For applications to quasi-exactly solvable Schrödinger equations in quantum mechanics, we consider the general conditions that have to be satisfied by the coefficients of a second-order differential equation with at most <em>k </em>+ 1 singular points in order that this equation has particular solutions that are <em>n</em>th-degree polynomials. In a first approach, we show that such conditions involve <em>k </em>- 2 integration constants, which satisfy a system of linear equations whose coefficients can be written in terms of elementary symmetric polynomials in the polynomial solution roots whenver such roots are all real and distinct. In a second approach, we consider the functional Bethe ansatz method in its most general form under the same assumption. Comparing the two approaches, we prove that the above-mentioned <em>k </em>- 2 integration constants can be expressed as linear combinations of monomial symmetric polynomials in the roots, associated with partitions into no more than two parts. We illustrate these results by considering a quasi-exactly solvable extension of the Mathews-Lakshmanan nonlinear oscillator corresponding to <em>k </em>= 4.

scholarly journals A NEW GENERAL APPROXIMATION SCHEME IN QUANTUM THEORY: APPLICATION TO THE ANHARMONIC AND THE DOUBLE WELL OSCILLATORS

2005 ◽  
Vol 20 (12) ◽  
pp. 2687-2714 ◽  
Author(s):  
B. P. MAHAPATRA ◽  
N. SANTI ◽  
N. B. PRADHAN
Keyword(s):  
Perturbation Theory ◽  
Approximation Scheme ◽  
Energy Levels ◽  
Exact Results ◽  
Exact Solvability ◽  
Exactly Solvable ◽  
Anharmonic Potential ◽  
Theory Application ◽  
Suitable Potential ◽  
Partner Potential

A self-consistent, nonperturbative approximation scheme is proposed which is potentially applicable to arbitrary interacting quantum systems. For the case of self-interaction, the scheme consists in approximating the original interaction HI(ϕ) by a suitable "potential" V(ϕ) which satisfies the following two basic requirements, (i) exact solvability (ES): the "effective" Hamiltonian H0 generated by V(ϕ) is exactly solvable i.e., the spectrum of states |n〉 and the eigenvalues En are known and (ii) equality of quantum averages (EQA): 〈n|HI(ϕ)|n〉 = 〈n|V(ϕ)|n〉 for arbitrary n. The leading order (LO) results for |n〉 and En are thus readily obtained and are found to be accurate to within a few percent of the "exact" results. These LO-results are systematically improvable by the construction of an improved perturbation theory (IPT) with the choice of H0 as the unperturbed Hamiltonian and the modified interaction, λH′(ϕ)≡λ(HI(ϕ) - V(ϕ)), as the perturbation where λ is the coupling strength. The condition of convergence of the IPT for arbitrary λ is satisfied due to the EQA requirement which ensures that 〈n|λH′(ϕ)|n〉 = 0for arbitrary λ and n. This is in contrast to the divergence (which occurs even for infinitesimal λ!) in the naive perturbation theory where the original interaction λHI(ϕ) is chosen as the perturbation. We apply the method to the different cases of the anharmonic and the double well potentials, e.g. quartic-, sextic- and octic-anharmonic oscillators and quartic-, sextic-double well oscillators. Uniformly accurate results for the energy levels over the full allowed range of λ and n are obtained. The results compare well with the exact results predicted by supersymmetry for the case of the sextic anharmonic potential and the double well partner potential. Further improvement in the accuracy of the results by the use of IPT, is demonstrated. We also discuss the vacuum structure and stability of the resulting theory in the above approximation scheme.

scholarly journals Target space entanglement in quantum mechanics of fermions and matrices

2021 ◽  
Vol 2021 (8) ◽  
Author(s):  
Sotaro Sugishita
Keyword(s):  
Mutual Information ◽  
Ground State ◽  
Entanglement Entropy ◽  
Algebraic Approach ◽  
Upper Bounds ◽  
Wave Functions ◽  
Target Space ◽  
Single Interval ◽  
Area Law ◽  
Formula Expression

Abstract We consider entanglement of first-quantized identical particles by adopting an algebraic approach. In particular, we investigate fermions whose wave functions are given by the Slater determinants, as for singlet sectors of one-matrix models. We show that the upper bounds of the general Rényi entropies are N log 2 for N particles or an N × N matrix. We compute the target space entanglement entropy and the mutual information in a free one-matrix model. We confirm the area law: the single-interval entropy for the ground state scales as $$ \frac{1}{3} $$ 1 3 log N in the large N model. We obtain an analytical $$ \mathcal{O}\left({N}^0\right) $$ O N 0 expression of the mutual information for two intervals in the large N expansion.

A free-electron theory of conjugated molecules

1953 ◽  
Vol 49 (4) ◽  
pp. 650-658 ◽  
Author(s):  
J. Stanley Griffith
Keyword(s):  
Free Electron ◽  
Wave Functions ◽  
Electron Charge ◽  
Algebraic Equations ◽  
Electron Wave ◽  
Electron Theory ◽  
Conjugated Molecules ◽  
Electron Charge Density ◽  
Linear Polyenes ◽  
Alternant Hydrocarbons

ABSTRACTThe values of a free-electron eigenfunotion at the carbon nuclei of a conjugated hydrocarbon are found to satisfy a system of algebraic equations. These equations are similar in form to those obtained in the method known as the linear combination of atomic orbitale but only coincide with them for linear polyenes and benzene. The symmetry, degeneracy and energy of the eigenvectors of these free-electron equations correspond exactly to those of the free-electron wave functions found by the usual methods. From this correspondence, a theorem is deduced about the free-electron charge density in alternant hydrocarbons.

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