Electron. J. Diff. Eqns., Vol. 1998(1998), No. 20, pp. 1-20.

The Schrodinger equation on non-stationary domains

Gunther Karner

We investigate the dynamical effects of non-stationary boundaries on the stability of a quantum Hamiltonian system described by a periodic family $\{H(\gamma,t), t\in[0,\Gamma],\Gamma positive\}$ of Sturm-Liouville operators, a Schrodinger equation $i\partial_{t}\psi = H(\gamma,t)\psi$ defined on
$$\Omega (a) = \left\{(t,x)\in{\Bbb R}^2 : x\in{(a(t),\infty)}, 
     a\in{\cal C}^3({\Bbb R}),a(t)=a(t+k\Gamma), k\in{\Bbb Z}\right\}\,,$$
as well as boundary conditions at $x=a(t)$ modeled by the $\Gamma$-periodic function $\gamma$. Employing extended Hilbert space methods, stability conditions for the spectra of the evolution operators ${\cal U}(a,\gamma,\Gamma,0)$ to the families $\bigl\{H(\gamma,t)\}$ under perturbations induced by variations of boundary oscillations, respectively conditions, are derived. In particular, it is shown that the existence of a pure point finitely degenerate realization ${\cal U}(a,\hat{\gamma},\Gamma,0))$ implies pure point ${\cal U}(a,\gamma,\Gamma,0)$ for all $\gamma\in{\cal C}^1({\Bbb R}), a\in{\cal C}^3({\Bbb R})$, whereas in case of infinitely degenerate $\sigma_{pp}\bigl({\cal U}(a,\hat{\gamma},\Gamma,0)\bigr)$ the existence of $\sigma_{{\rm ac}}\bigl({\cal U}(a,\gamma,\Gamma,0)\bigr)\neq\emptyset$, respectively $\sigma_{sc}\bigl({\cal U}(a,\gamma,\Gamma,0)\bigr)\neq\emptyset$, is possible.

Submitted December 18, 1997. Published July 17, 1998.
Math Subject Classification: 35P05, 81Q10.
Key Words: Stability of dense point spectra, boundary induced perturbations, Krein's resolvent formula.

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Gunther Karner
Institut fur Kerntechnik und Reaktorsicherheit
Universitat Karlsruhe (TH), Postfach 3640
D - 76021 Karlsruhe, Germany
e-mail: karner@irs.fzk.de
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