VIII.—The Schrödinger Equation with a Periodic Potential

Author(s):  
M. S. P. Eastham

SynopsisThe differential equationin N dimensions is considered, where q(x) is periodic. When N = 1, it is known that the conditional stability set coincides with the spectrum and that these also coincide with two other sets involving eigenvalues of associated eigenvalue problems. These results have been proved by means of the Floquet theory and the discriminant. Here an alternative proof is given which avoids the Floquet theory and which applies to the general case of N dimensions.

Author(s):  
E. M. de Jager ◽  
T. Küpper

SynopsisComparisons have been made of the eigenvalues and the corresponding eigenfunctions of the eigenvalue problemsandwith φ ∈ C(-∞, +∞) and 0≦φ(x)≦C|x|i+1(1+|x|1), −∞<x<+∞ where i and l are arbitrary positive numbers with i≧2k≧2, k integer. In first approximation the eigenvalues λ and λ− and the corresponding eigenfunctions ψ and ψ are the same for ε→0; the error decreases whenever the exponent i increases.


1983 ◽  
Vol 50 (23) ◽  
pp. 1873-1876 ◽  
Author(s):  
Stellan Ostlund ◽  
Rahul Pandit ◽  
David Rand ◽  
Hans Joachim Schellnhuber ◽  
Eric D. Siggia

1988 ◽  
Vol 109 (1-2) ◽  
pp. 109-126 ◽  
Author(s):  
Peter A. Clarkson

SynopsisIn this paper we apply the Painlevé tests to the damped, driven nonlinear Schrödinger equationwhere a(x, t) and b(x, t) are analytic functions of x and t, todetermine under what conditions the equation might be completely integrable. It is shown that (0.1) can pass the Painlevé tests only ifwhere α0(t),α1(t) and β(t) are arbitrary, real analytic functions of time. Furthermore, it is shown that in this special case, (0.1) may be transformed into the original nonlinear Schrödinger equation, which is known to be completely integrable.


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