scholarly journals On the variational principle for the non-linear Schrödinger equation

2019 ◽  
Vol 58 (1) ◽  
pp. 340-351
Author(s):  
Zsuzsanna É. Mihálka ◽  
Ádám Margócsy ◽  
Ágnes Szabados ◽  
Péter R. Surján

AbstractWhile variation of the energy functional yields the Schrödinger equation in the usual, linear case, no such statement can be formulated in the general nonlinear situation when the Hamiltonian depends on its eigenvector. In this latter case, as we illustrate by sample numerical calculations, the points of the energy expectation value hypersurface where the eigenvalue equation is satisfied separate from those where the energy is stationary. We show that the variation of the energy at the eigensolution is determined by a generalized Hellmann–Feynman theorem. Functionals, other than the energy, can, however be constructed, that result the nonlinear Schrödinger equation upon setting their variation zero. The second centralized moment of the Hamiltonian is one example.

Author(s):  
Ji-Huan He ◽  
Chun-Hui He ◽  
Tareq Saeed

The Chen–Lee–Liu equation is a modified Schrödinger equation to describe a solitary wave of ultrashort pulses in optics, which lead to a discontinuous time, so a fractal modification is suggested and a fractal variational principle is established by the semi-inverse method.


2003 ◽  
Vol 18 (02n06) ◽  
pp. 139-142
Author(s):  
H. NEMURA ◽  
Y. AKAISHI ◽  
Y. SUZUKI

Variational calculations for s-shell hypernuclei are performed by explicitly including Σ degrees of freedom. Two sets of YN interactions (D2 and SC97e(S)) are used. The bound-state solution of [Formula: see text] is obtained by using each of YN potentials, and a large energy expectation value of the tensor ΛN - ΣN transition part is found by using the SC97e(S). The internal energy of 4 He subsystem changes a lot by the presence of a Λ particle with the strong tensor ΛN - ΣN transition potential.


2015 ◽  
Vol 58 (3) ◽  
pp. 697-716 ◽  
Author(s):  
Liliane A. Maia ◽  
Olimpio H. Miyagaki ◽  
Sergio H. M. Soares

AbstractThe aim of this paper is to present a sign-changing solution for a class of radially symmetric asymptotically linear Schrödinger equations. The proof is variational and the Ekeland variational principle is employed as well as a deformation lemma combined with Miranda’s theorem.


2006 ◽  
Vol 84 (10) ◽  
pp. 905-923 ◽  
Author(s):  
P Gulshani

In this article, a semiclassical, microscopic model (dubbed SMRM) is derived to describe collective rotation in deformed nuclei. The SMRM is derived by transforming the time-dependent, multiparticle Schrodinger equation to a rotating frame whose axes are chosen to coincide with the principal axes of the expectation value of an arbitrary, second-rank, symmetric, tensor (nuclear shape) operator [Formula: see text]. This transformation circumvents the difficulty associated with the introduction of redundant particle coordinates in the Villars' transformation. The SMRM Schrodinger equation, which resembles the cranking model (CM) equation, is a time-dependent, time-reversal-invariant, nonlinear integro-differential equation. In this equation, the angular velocity is determined by the wave function and deformation–rotation shear operators, and this introduces the nonlinearity in the equation. A variational method is proposed and justified to obtain: a stationary solution of the SMRM Schrodinger equation in the Rayleigh–Ritz Hartree–Fock particle–hole formalism, the rotational energy increment, and the associated moment of inertia. When exchange interaction terms are neglected or a separable interaction is used, the SMRM moment of inertia is shown to reduce to that given by the CM provided that a certain relationship exists between the moment of inertia and the expectation value of [Formula: see text]. However, the SMRM and CM wave functions are not the same (SMRM preserves and CM violates time-reversal invariance) implying that the calculated values of other parameters, including the moment of inertia at higher values of the angular momentum, may not be the same in the two models. In any case, the SMRM derives the CM moment of inertia from a microscopic, time-reversal invariant, nonlinear theory.PACS Nos.: 21.60.Ev, 21.60.Fw, 21.60.Jz


2010 ◽  
Vol 7 (1) ◽  
pp. 115-122
Author(s):  
Eman Salem A. Alaidarous

The generators of the admitted variational Lie symmetry groups are derived and conservation laws for the conserved currents are obtained via Noether's theorem. Moreover, the consistency of a functional integral are derived for the nonlinear Schrödinger equation. In addition to this analysis functional integral are studied using Lie groups.


2015 ◽  
Vol 12 (2) ◽  
pp. 394-399
Author(s):  
Baghdad Science Journal

The purpose of the present work is to calculate the expectation value of potential energy for different spin states (??? ? ???,??? ? ???) and compared it with spin states (??? , ??? ) for lithium excited state (1s2s3s) and Li- like ions (Be+,B+2) using Hartree-Fock wave function by partitioning techanique .The result of inter particle expectation value shows linear behaviour with atomic number and for each atom and ion the shows the trend ??? < ??? < ??? < ???


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