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1D Schr\"odinger operator with periodic plus compactly supported potentials

Spectral Theory 2009-04-21 v1 Mathematical Physics math.MP

Abstract

We consider the 1D Schr\"odinger operator Hy=y+(p+q)yHy=-y''+(p+q)y with a periodic potential pp plus compactly supported potential qq on the real line. The spectrum of HH consists of an absolutely continuous part plus a finite number of simple eigenvalues in each spectral gap \gn\es,n0\g_n\ne \es, n\geq 0, where \g0\g_0 is unbounded gap. We prove the following results: 1) we determine the distribution of resonances in the disk with large radius, 2) a forbidden domain for the resonances is specified, 3) the asymptotics of eigenvalues and antibound states are determined, 4) if q0=Rqdx=0q_0=\int_\R qdx=0, then roughly speaking in each nondegenerate gap \gn\g_n for nn large enough there are two eigenvalues and zero antibound state or zero eigenvalues and two antibound states, 5) if HH has infinitely many gaps in the continuous spectrum, then for any sequence \s=(\s)1\iy,\sn{0,2}\s=(\s)_1^\iy, \s_n\in \{0,2\}, there exists a compactly supported potential qq such that HH has \sn\s_n bound states and 2\sn2-\s_n antibound states in each gap \gn\g_n for nn large enough. 6) For any qq (with q0=0q_0=0), \s=(\sn)1\iy\s=(\s_n)_{1}^\iy, where \sn{0,2}\s_n\in \{0,2\} and for any sequence \d=(\dn)1\iy2,\dn>0\d=(\d_n)_1^\iy\in \ell^2, \d_n>0 there exists a potential pL2(0,1)p\in L^2(0,1) such that each gap length \gn=\dn,n1|\g_n|=\d_n, n\ge 1 and HH has exactly \sn\s_n eigenvalues and 2\sn2-\s_n antibound states in each gap \gn\es\g_n\ne \es for nn large enough.

Keywords

Cite

@article{arxiv.0904.2871,
  title  = {1D Schr\"odinger operator with periodic plus compactly supported potentials},
  author = {Evgeny Korotyaev},
  journal= {arXiv preprint arXiv:0904.2871},
  year   = {2009}
}

Comments

18 pages

R2 v1 2026-06-21T12:52:50.537Z