<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE article PUBLIC "-//NLM//DTD JATS (Z39.96) Journal Publishing DTD v1.3 20210610//EN" "JATS-journalpublishing1-3.dtd">
<article article-type="research-article" dtd-version="1.3" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xml:lang="en"><front><journal-meta><journal-id journal-id-type="publisher-id">najo</journal-id><journal-title-group><journal-title xml:lang="en">Nanosystems: Physics, Chemistry, Mathematics</journal-title><trans-title-group xml:lang="ru"><trans-title>Наносистемы: физика, химия, математика</trans-title></trans-title-group></journal-title-group><issn pub-type="ppub">2220-8054</issn><issn pub-type="epub">2305-7971</issn><publisher><publisher-name>Университет ИТМО</publisher-name></publisher></journal-meta><article-meta><article-id custom-type="elpub" pub-id-type="custom">najo-1174</article-id><article-categories><subj-group subj-group-type="heading"><subject>Research Article</subject></subj-group><subj-group subj-group-type="section-heading" xml:lang="en"><subject>MATHEMATICS</subject></subj-group><subj-group subj-group-type="section-heading" xml:lang="ru"><subject>МАТЕМАТИКА</subject></subj-group></article-categories><title-group><article-title>Nonlinearity-defect interaction: symmetry breaking bifurcation in a NLS with a 𝛿′ impurity</article-title><trans-title-group xml:lang="ru"><trans-title></trans-title></trans-title-group></title-group><contrib-group><contrib contrib-type="author" corresp="yes"><name-alternatives><name name-style="western" xml:lang="en"><surname>Adami</surname><given-names>R.</given-names></name></name-alternatives><bio xml:lang="en"><p>Riccardo Adami – Dipartimento di Matematica e Applicazioni, Assistant Professor</p></bio><email xlink:type="simple">riccardo.adami@unimib.it</email><xref ref-type="aff" rid="aff-1"/></contrib><contrib contrib-type="author" corresp="yes"><name-alternatives><name name-style="western" xml:lang="en"><surname>Noja</surname><given-names>D.</given-names></name></name-alternatives><bio xml:lang="en"><p>Diego Noja – Dipartimento di Matematica e Applicazioni, Assistant Professor</p></bio><email xlink:type="simple">diego.noja@unimib.it</email><xref ref-type="aff" rid="aff-1"/></contrib></contrib-group><aff xml:lang="en" id="aff-1"><institution>Universit`a di Milano Bicocca</institution><country>Italy</country></aff><pub-date pub-type="collection"><year>2011</year></pub-date><pub-date pub-type="epub"><day>18</day><month>08</month><year>2025</year></pub-date><volume>2</volume><issue>4</issue><fpage>5</fpage><lpage>19</lpage><permissions><copyright-statement>Copyright &amp;#x00A9; Adami R., Noja D., 2025</copyright-statement><copyright-year>2025</copyright-year><copyright-holder xml:lang="ru">Adami R., Noja D.</copyright-holder><copyright-holder xml:lang="en">Adami R., Noja D.</copyright-holder><license xml:lang="ru" license-type="creative-commons-attribution" xlink:href="https://creativecommons.org/licenses/by/4.0/" xlink:type="simple"><license-p>Данная работа распространяется под лицензией Creative Commons Attribution 4.0.</license-p></license><license xml:lang="en" license-type="creative-commons-attribution" xlink:href="https://creativecommons.org/licenses/by/4.0/" xlink:type="simple"><license-p>This work is licensed under a Creative Commons Attribution 4.0 License.</license-p></license></permissions><self-uri xlink:href="https://nanojournal.ifmo.ru/jour/article/view/1174">https://nanojournal.ifmo.ru/jour/article/view/1174</self-uri><abstract><p>We illustrate some new results and comment on perspectives of a recent research line, focused on the stability of stationary states of nonlinear NLS with point interactions. We describe in detail the case of a “𝛿′” interaction, that provides a rich model endowed with a pitchfork bifurcation with symmetry breaking in the family of ground states. Finally, we give a direct proof of the stability of the ground states in the cases of a subcritical and critical (in the sense of the blow-up) nonlinearity power. </p></abstract><kwd-group xml:lang="en"><kwd>nonlinear dynamics</kwd><kwd>quantum mechanics</kwd><kwd>solitons</kwd><kwd>symmetry breaking</kwd><kwd>pitchfork bifurcation</kwd></kwd-group></article-meta></front><back><ref-list><title>References</title><ref id="cit1"><label>1</label><citation-alternatives><mixed-citation xml:lang="ru">Adami R., Bardos C., Golse. F, Teta A. Towards a rigorous derivation of the cubic NLSE in dimension one // Asymp. An. — 2004. — V. 40(2). — P. 93-108.</mixed-citation><mixed-citation xml:lang="en">Adami R., Bardos C., Golse. F, Teta A. Towards a rigorous derivation of the cubic NLSE in dimension one // Asymp. An. — 2004. — V. 40(2). — P. 93-108.</mixed-citation></citation-alternatives></ref><ref id="cit2"><label>2</label><citation-alternatives><mixed-citation xml:lang="ru">Adami R., Golse, F, Teta A.: Rigorous derivation of the cubic NLS in dimension one // J. Stat. Phys. — 2007. — V. 127. — P. 1193-1220.</mixed-citation><mixed-citation xml:lang="en">Adami R., Golse, F, Teta A.: Rigorous derivation of the cubic NLS in dimension one // J. Stat. Phys. — 2007. — V. 127. — P. 1193-1220.</mixed-citation></citation-alternatives></ref><ref id="cit3"><label>3</label><citation-alternatives><mixed-citation xml:lang="ru">Adami R., Noja D. Existence of dynamics for a 1-d NLS equation in dimension one // J. Phys. A Math. Theor. — 2009. — V. 42. — 495302, 19 p.</mixed-citation><mixed-citation xml:lang="en">Adami R., Noja D. Existence of dynamics for a 1-d NLS equation in dimension one // J. Phys. A Math. Theor. — 2009. — V. 42. — 495302, 19 p.</mixed-citation></citation-alternatives></ref><ref id="cit4"><label>4</label><citation-alternatives><mixed-citation xml:lang="ru">Adami R., Cacciapuoti C., Finco D., Noja D. Fast Solitons on Star Graphs // Rev. Math. Phys. — 2011. — V. 23(4).</mixed-citation><mixed-citation xml:lang="en">Adami R., Cacciapuoti C., Finco D., Noja D. Fast Solitons on Star Graphs // Rev. Math. Phys. — 2011. — V. 23(4).</mixed-citation></citation-alternatives></ref><ref id="cit5"><label>5</label><citation-alternatives><mixed-citation xml:lang="ru">Adami R., Cacciapuoti C., Finco D., Noja D. Stationary states of NLS on star graphs. — arXiv: 1104.3839, 2011.</mixed-citation><mixed-citation xml:lang="en">Adami R., Cacciapuoti C., Finco D., Noja D. Stationary states of NLS on star graphs. — arXiv: 1104.3839, 2011.</mixed-citation></citation-alternatives></ref><ref id="cit6"><label>6</label><citation-alternatives><mixed-citation xml:lang="ru">Adami R., Noja D. Stability, instability and symmetry breaking bifurcation for the ground states of a NLS with a 𝛿′ interaction // arXiv.1112.1318, 2011.</mixed-citation><mixed-citation xml:lang="en">Adami R., Noja D. Stability, instability and symmetry breaking bifurcation for the ground states of a NLS with a 𝛿′ interaction // arXiv.1112.1318, 2011.</mixed-citation></citation-alternatives></ref><ref id="cit7"><label>7</label><citation-alternatives><mixed-citation xml:lang="ru">Adami R., Noja D., Sacchetti A. On the mathematical description of the effective behaviour of one-dimensional Bose-Einstein condensates with defects // In: Bose-Einstein Condensates: Theory, Characteristics, and Current Research. — New York: Nova Publishing, 2010.</mixed-citation><mixed-citation xml:lang="en">Adami R., Noja D., Sacchetti A. On the mathematical description of the effective behaviour of one-dimensional Bose-Einstein condensates with defects // In: Bose-Einstein Condensates: Theory, Characteristics, and Current Research. — New York: Nova Publishing, 2010.</mixed-citation></citation-alternatives></ref><ref id="cit8"><label>8</label><citation-alternatives><mixed-citation xml:lang="ru">Adami R., Sacchetti A. The transition from diffusion to blow-up for a NLS equation in dimension one // J. Phys. A Math. Gen. — 2005. — V. 38. — P. 8379-8392.</mixed-citation><mixed-citation xml:lang="en">Adami R., Sacchetti A. The transition from diffusion to blow-up for a NLS equation in dimension one // J. Phys. A Math. Gen. — 2005. — V. 38. — P. 8379-8392.</mixed-citation></citation-alternatives></ref><ref id="cit9"><label>9</label><citation-alternatives><mixed-citation xml:lang="ru">Albeverio S., Brze´zniak Z., Dabrowski L. Fundamental solutions of the Heat and Schr¨odinger Equations with point interaction // Journal of Functional Analysis. — 1995. — V. 130. — P. 220-254.</mixed-citation><mixed-citation xml:lang="en">Albeverio S., Brze´zniak Z., Dabrowski L. Fundamental solutions of the Heat and Schr¨odinger Equations with point interaction // Journal of Functional Analysis. — 1995. — V. 130. — P. 220-254.</mixed-citation></citation-alternatives></ref><ref id="cit10"><label>10</label><citation-alternatives><mixed-citation xml:lang="ru">Albeverio S., Gesztesy F., Hoegh-Krohn R., Holden H. Solvable Models in Quantum Mechanics: Second Edition, With an Appendix by Pavel Exner. — AMS Chelsea Publishing, Providence, 2005.</mixed-citation><mixed-citation xml:lang="en">Albeverio S., Gesztesy F., Hoegh-Krohn R., Holden H. Solvable Models in Quantum Mechanics: Second Edition, With an Appendix by Pavel Exner. — AMS Chelsea Publishing, Providence, 2005.</mixed-citation></citation-alternatives></ref><ref id="cit11"><label>11</label><citation-alternatives><mixed-citation xml:lang="ru">Albeverio S., Kurasov P. Singular Perturbations of Differential Operators. — Cambridge University Press, 2000.</mixed-citation><mixed-citation xml:lang="en">Albeverio S., Kurasov P. Singular Perturbations of Differential Operators. — Cambridge University Press, 2000.</mixed-citation></citation-alternatives></ref><ref id="cit12"><label>12</label><citation-alternatives><mixed-citation xml:lang="ru">Ammari Z., Breteaux S. Propagation of chaos for many-boson systems in one dimension with a point pairinteraction. — arXiv: 0906.3047, 2009.</mixed-citation><mixed-citation xml:lang="en">Ammari Z., Breteaux S. Propagation of chaos for many-boson systems in one dimension with a point pairinteraction. — arXiv: 0906.3047, 2009.</mixed-citation></citation-alternatives></ref><ref id="cit13"><label>13</label><citation-alternatives><mixed-citation xml:lang="ru">Brazhnyi V., Konotop V., Perez-Garc´ıa V. Driving defect modes of Bose Einstein condensates in optical lattices // Phys. Rev.Lett. — 2006. — 96. 060403.</mixed-citation><mixed-citation xml:lang="en">Brazhnyi V., Konotop V., Perez-Garc´ıa V. Driving defect modes of Bose Einstein condensates in optical lattices // Phys. Rev.Lett. — 2006. — 96. 060403.</mixed-citation></citation-alternatives></ref><ref id="cit14"><label>14</label><citation-alternatives><mixed-citation xml:lang="ru">Brazhnyi V., Konotop V., Perez-Garc´ıa V. Defect modes of a Bose Einstein condensate in an optical lattice with a localized impurity // Phys. Rev.A. — 2006. — V. 74. — 023614.</mixed-citation><mixed-citation xml:lang="en">Brazhnyi V., Konotop V., Perez-Garc´ıa V. Defect modes of a Bose Einstein condensate in an optical lattice with a localized impurity // Phys. Rev.A. — 2006. — V. 74. — 023614.</mixed-citation></citation-alternatives></ref><ref id="cit15"><label>15</label><citation-alternatives><mixed-citation xml:lang="ru">Brezis H., Lieb E.H. A relation between pointwise convergence of functions and convergence of functionals // Proc. Amer. Math. Soc. — 1983. — V. 88. — P. 486–490.</mixed-citation><mixed-citation xml:lang="en">Brezis H., Lieb E.H. A relation between pointwise convergence of functions and convergence of functionals // Proc. Amer. Math. Soc. — 1983. — V. 88. — P. 486–490.</mixed-citation></citation-alternatives></ref><ref id="cit16"><label>16</label><citation-alternatives><mixed-citation xml:lang="ru">Burioni R., Cassi D., Sodano P., Trombettoni A., Vezzani A. Soliton propagation on chains with simple nonlocal defects // Physica D –. 2006. — V. 216. — P. 71–76.</mixed-citation><mixed-citation xml:lang="en">Burioni R., Cassi D., Sodano P., Trombettoni A., Vezzani A. Soliton propagation on chains with simple nonlocal defects // Physica D –. 2006. — V. 216. — P. 71–76.</mixed-citation></citation-alternatives></ref><ref id="cit17"><label>17</label><citation-alternatives><mixed-citation xml:lang="ru">Cazenave T. Semilinear Schr¨odinger Equations. — Courant Lecture Notes, 2003.</mixed-citation><mixed-citation xml:lang="en">Cazenave T. Semilinear Schr¨odinger Equations. — Courant Lecture Notes, 2003.</mixed-citation></citation-alternatives></ref><ref id="cit18"><label>18</label><citation-alternatives><mixed-citation xml:lang="ru">Cheon T., Shigehara T. Realizing discontinuous wave functions with renormalized short-range potentials // Phys. Lett. A. — 1998. — V. 243(22). — P. 111–116.</mixed-citation><mixed-citation xml:lang="en">Cheon T., Shigehara T. Realizing discontinuous wave functions with renormalized short-range potentials // Phys. Lett. A. — 1998. — V. 243(22). — P. 111–116.</mixed-citation></citation-alternatives></ref><ref id="cit19"><label>19</label><citation-alternatives><mixed-citation xml:lang="ru">Datchev K., Holmer J. Fast soliton scattering by attractive delta impurities // Comm. Part. Diff. Eq. — 2009. — V. 34. — P. 1074-1113.</mixed-citation><mixed-citation xml:lang="en">Datchev K., Holmer J. Fast soliton scattering by attractive delta impurities // Comm. Part. Diff. Eq. — 2009. — V. 34. — P. 1074-1113.</mixed-citation></citation-alternatives></ref><ref id="cit20"><label>20</label><citation-alternatives><mixed-citation xml:lang="ru">Erd˝os L., Schlein B., Yau H-T. Derivation of the Gross-Pitaevskii hierarchy for the dynamics of the Bose Einstein condensate // Comm. Pure Appl. Math. — 2006. — V. 59. — P. 1659–1741.</mixed-citation><mixed-citation xml:lang="en">Erd˝os L., Schlein B., Yau H-T. Derivation of the Gross-Pitaevskii hierarchy for the dynamics of the Bose Einstein condensate // Comm. Pure Appl. Math. — 2006. — V. 59. — P. 1659–1741.</mixed-citation></citation-alternatives></ref><ref id="cit21"><label>21</label><citation-alternatives><mixed-citation xml:lang="ru">Erd˝os L., Schlein B., Yau H-T. Derivation of the cubic nonlinear Schr¨odinger equation from quantum dynamics of many body systems // Invent. Math. — 2007. — V. 167. — P. 515–614.</mixed-citation><mixed-citation xml:lang="en">Erd˝os L., Schlein B., Yau H-T. Derivation of the cubic nonlinear Schr¨odinger equation from quantum dynamics of many body systems // Invent. Math. — 2007. — V. 167. — P. 515–614.</mixed-citation></citation-alternatives></ref><ref id="cit22"><label>22</label><citation-alternatives><mixed-citation xml:lang="ru">Erd˝os L., Schlein B., Yau H-T. Derivation of the Gross-Pitaevskii equation for the dynamics of the Bose Einstein condensate. // Ann. Math. — 2010. — V. 172(1). — P. 291-370.</mixed-citation><mixed-citation xml:lang="en">Erd˝os L., Schlein B., Yau H-T. Derivation of the Gross-Pitaevskii equation for the dynamics of the Bose Einstein condensate. // Ann. Math. — 2010. — V. 172(1). — P. 291-370.</mixed-citation></citation-alternatives></ref><ref id="cit23"><label>23</label><citation-alternatives><mixed-citation xml:lang="ru">Exner P., Grosse P. Some properties of the one-dimensional generalized point interactions (a torso). — mp-arc 99-390, math-ph/9910029, 1999.</mixed-citation><mixed-citation xml:lang="en">Exner P., Grosse P. Some properties of the one-dimensional generalized point interactions (a torso). — mp-arc 99-390, math-ph/9910029, 1999.</mixed-citation></citation-alternatives></ref><ref id="cit24"><label>24</label><citation-alternatives><mixed-citation xml:lang="ru">Exner P. Neidhart H. Zagrebnov V.A. Potential approximations to 𝛿′: an inverse Klauder phenomenon with norm-resolvent convergence // Comm. Math. Phys. — 2001. — V. 224. — P. 593–612.</mixed-citation><mixed-citation xml:lang="en">Exner P. Neidhart H. Zagrebnov V.A. Potential approximations to 𝛿′: an inverse Klauder phenomenon with norm-resolvent convergence // Comm. Math. Phys. — 2001. — V. 224. — P. 593–612.</mixed-citation></citation-alternatives></ref><ref id="cit25"><label>25</label><citation-alternatives><mixed-citation xml:lang="ru">Fibich G., Wang X. P. Stability for solitary waves for nonlinear Schr¨odinger equations with inhomogenous nonlinearities // Physica D. — 2003. — V. 175. — P. 96-108.</mixed-citation><mixed-citation xml:lang="en">Fibich G., Wang X. P. Stability for solitary waves for nonlinear Schr¨odinger equations with inhomogenous nonlinearities // Physica D. — 2003. — V. 175. — P. 96-108.</mixed-citation></citation-alternatives></ref><ref id="cit26"><label>26</label><citation-alternatives><mixed-citation xml:lang="ru">Fukuizumi R., Jeanjean L.: Stability of standing waves for a nonlinear Schr¨odinger equation with a repulsive Dirac delta potential // Disc. Cont. Dyn. Syst. (A). — 2008. — 21. — P. 129-144.</mixed-citation><mixed-citation xml:lang="en">Fukuizumi R., Jeanjean L.: Stability of standing waves for a nonlinear Schr¨odinger equation with a repulsive Dirac delta potential // Disc. Cont. Dyn. Syst. (A). — 2008. — 21. — P. 129-144.</mixed-citation></citation-alternatives></ref><ref id="cit27"><label>27</label><citation-alternatives><mixed-citation xml:lang="ru">Fukuizumi R., Ohta M, Ozawa T. Nonlinear Schr¨odinger equation with a point defect // Ann. I.H.Poincar´e, AN. — 2008. — 25. — P. 837-845.</mixed-citation><mixed-citation xml:lang="en">Fukuizumi R., Ohta M, Ozawa T. Nonlinear Schr¨odinger equation with a point defect // Ann. I.H.Poincar´e, AN. — 2008. — 25. — P. 837-845.</mixed-citation></citation-alternatives></ref><ref id="cit28"><label>28</label><citation-alternatives><mixed-citation xml:lang="ru">Fukuizumi R., Sacchetti A. Bifurcation and stability for Nonlinear Schroedinger equations with double well potential in the semiclassical limit, preprint arXiv:1104.1511 (2011).</mixed-citation><mixed-citation xml:lang="en">Fukuizumi R., Sacchetti A. Bifurcation and stability for Nonlinear Schroedinger equations with double well potential in the semiclassical limit, preprint arXiv:1104.1511 (2011).</mixed-citation></citation-alternatives></ref><ref id="cit29"><label>29</label><citation-alternatives><mixed-citation xml:lang="ru">Goodman R. H., Holmes P. J., Weinstein M. I. Strong NLS soliton-defect interactions // Physica D. — 2004. — 192. — P. 215-248.</mixed-citation><mixed-citation xml:lang="en">Goodman R. H., Holmes P. J., Weinstein M. I. Strong NLS soliton-defect interactions // Physica D. — 2004. — 192. — P. 215-248.</mixed-citation></citation-alternatives></ref><ref id="cit30"><label>30</label><citation-alternatives><mixed-citation xml:lang="ru">Grillakis M. Shatah J. Strauss W. Stability theory of solitary waves in the presence of symmetry I. // J. Func. An. — 1987. — V. 74. — P. 160-197.</mixed-citation><mixed-citation xml:lang="en">Grillakis M. Shatah J. Strauss W. Stability theory of solitary waves in the presence of symmetry I. // J. Func. An. — 1987. — V. 74. — P. 160-197.</mixed-citation></citation-alternatives></ref><ref id="cit31"><label>31</label><citation-alternatives><mixed-citation xml:lang="ru">Grillakis M. Shatah J. Strauss W. Stability theory of solitary waves in the presence of symmetry II // J. Func. An. — 1990. — V. 94. — P. 308-348.</mixed-citation><mixed-citation xml:lang="en">Grillakis M. Shatah J. Strauss W. Stability theory of solitary waves in the presence of symmetry II // J. Func. An. — 1990. — V. 94. — P. 308-348.</mixed-citation></citation-alternatives></ref><ref id="cit32"><label>32</label><citation-alternatives><mixed-citation xml:lang="ru">Holmer J., Marzuola J., Zworski M. Fast soliton scattering by delta impurities // Comm. Math. Phys. — 2007. — V. 274. — P. 187-216.</mixed-citation><mixed-citation xml:lang="en">Holmer J., Marzuola J., Zworski M. Fast soliton scattering by delta impurities // Comm. Math. Phys. — 2007. — V. 274. — P. 187-216.</mixed-citation></citation-alternatives></ref><ref id="cit33"><label>33</label><citation-alternatives><mixed-citation xml:lang="ru">Jackson R.K, Weinstein M.I. Geometric analysis of bifurcation and symmetry breaking in a Gross-Pitaevskii equation // J. Stat. Phys. — 2004. — V. 116. — P. 881-905.</mixed-citation><mixed-citation xml:lang="en">Jackson R.K, Weinstein M.I. Geometric analysis of bifurcation and symmetry breaking in a Gross-Pitaevskii equation // J. Stat. Phys. — 2004. — V. 116. — P. 881-905.</mixed-citation></citation-alternatives></ref><ref id="cit34"><label>34</label><citation-alternatives><mixed-citation xml:lang="ru">Kirkpatrick K., Staffilani G., Schlein B. Derivation of the two-dimensional nonlinear Schr¨odinger equation from many body quantum dynamics // Am. J. of Math. — 2011. — V. 133(1). — P. 91-130.</mixed-citation><mixed-citation xml:lang="en">Kirkpatrick K., Staffilani G., Schlein B. Derivation of the two-dimensional nonlinear Schr¨odinger equation from many body quantum dynamics // Am. J. of Math. — 2011. — V. 133(1). — P. 91-130.</mixed-citation></citation-alternatives></ref><ref id="cit35"><label>35</label><citation-alternatives><mixed-citation xml:lang="ru">Kirr E.W., Kevrekidis P.G., Pelinovsky D. E. Symmetry-breaking bifurcation in the nonlinear Schrodinger equation with symmetric potentials. — arXiv:1012.3921, 2010.</mixed-citation><mixed-citation xml:lang="en">Kirr E.W., Kevrekidis P.G., Pelinovsky D. E. Symmetry-breaking bifurcation in the nonlinear Schrodinger equation with symmetric potentials. — arXiv:1012.3921, 2010.</mixed-citation></citation-alternatives></ref><ref id="cit36"><label>36</label><citation-alternatives><mixed-citation xml:lang="ru">Kirr E.W., Kevrekidis R.G., Shlizerman E., Weinstein M.I. Symmetry-breaking bifurcation in nonlinear Schr¨odinger/Gross–Pitaevskii equations // SIAM J. Math. Anal. — 2008. — V. 40. — P. 566-604.</mixed-citation><mixed-citation xml:lang="en">Kirr E.W., Kevrekidis R.G., Shlizerman E., Weinstein M.I. Symmetry-breaking bifurcation in nonlinear Schr¨odinger/Gross–Pitaevskii equations // SIAM J. Math. Anal. — 2008. — V. 40. — P. 566-604.</mixed-citation></citation-alternatives></ref><ref id="cit37"><label>37</label><citation-alternatives><mixed-citation xml:lang="ru">Kostrykin V., Schrader R. Kirchhoff’s rule for quantum wires // J. Phys. A: Math. Gen. — 1999. — V. 32(4). — P. 595-630.</mixed-citation><mixed-citation xml:lang="en">Kostrykin V., Schrader R. Kirchhoff’s rule for quantum wires // J. Phys. A: Math. Gen. — 1999. — V. 32(4). — P. 595-630.</mixed-citation></citation-alternatives></ref><ref id="cit38"><label>38</label><citation-alternatives><mixed-citation xml:lang="ru">Kuchment P. Quantum graphs. I. Some basic structures // Waves Random Media. — 2004. — V. 14(1). — S107–S128.</mixed-citation><mixed-citation xml:lang="en">Kuchment P. Quantum graphs. I. Some basic structures // Waves Random Media. — 2004. — V. 14(1). — S107–S128.</mixed-citation></citation-alternatives></ref><ref id="cit39"><label>39</label><citation-alternatives><mixed-citation xml:lang="ru">Kuchment P.: Quantum graphs. II. Some spectral properties of quantum and combinatorial graphs // J. Phys. A: Math. Gen. — 2005. — V. 38(22). — P. 4887-4900.</mixed-citation><mixed-citation xml:lang="en">Kuchment P.: Quantum graphs. II. Some spectral properties of quantum and combinatorial graphs // J. Phys. A: Math. Gen. — 2005. — V. 38(22). — P. 4887-4900.</mixed-citation></citation-alternatives></ref><ref id="cit40"><label>40</label><citation-alternatives><mixed-citation xml:lang="ru">Le Coz S., Fukuizumi ., Fibich G., Ksherim B., Sivan Y.: Instability of bound states of a nonlinear Schr¨odinger equation with a Dirac potential // Phys. D. — 2008. — V. 237(8). — P. 1103–1128.</mixed-citation><mixed-citation xml:lang="en">Le Coz S., Fukuizumi ., Fibich G., Ksherim B., Sivan Y.: Instability of bound states of a nonlinear Schr¨odinger equation with a Dirac potential // Phys. D. — 2008. — V. 237(8). — P. 1103–1128.</mixed-citation></citation-alternatives></ref><ref id="cit41"><label>41</label><citation-alternatives><mixed-citation xml:lang="ru">Lions, P.L. The concentration-compactness principle in the calculus of variations. The locally compact case. I // Ann. Inst. H. Poincar´e Anal. Non Lin´eaire. — 1984. — 1. — P. 109-145.</mixed-citation><mixed-citation xml:lang="en">Lions, P.L. The concentration-compactness principle in the calculus of variations. The locally compact case. I // Ann. Inst. H. Poincar´e Anal. Non Lin´eaire. — 1984. — 1. — P. 109-145.</mixed-citation></citation-alternatives></ref><ref id="cit42"><label>42</label><citation-alternatives><mixed-citation xml:lang="ru">Lions, P.L. The concentration-compactness principle in the calculus of variations. The locally compact case. II // Ann. Inst. H. Poincar´e Anal. Non Lin´eaire. — 1984. — V. 1. — P. 223-283.</mixed-citation><mixed-citation xml:lang="en">Lions, P.L. The concentration-compactness principle in the calculus of variations. The locally compact case. II // Ann. Inst. H. Poincar´e Anal. Non Lin´eaire. — 1984. — V. 1. — P. 223-283.</mixed-citation></citation-alternatives></ref><ref id="cit43"><label>43</label><citation-alternatives><mixed-citation xml:lang="ru">Pelinovsky D.E., Phan T. Normal form for the symmetry-breaking bifurcation in the nonlinear Schr¨odinger equation. — arXiv: 1101.5402v1, 2011.</mixed-citation><mixed-citation xml:lang="en">Pelinovsky D.E., Phan T. Normal form for the symmetry-breaking bifurcation in the nonlinear Schr¨odinger equation. — arXiv: 1101.5402v1, 2011.</mixed-citation></citation-alternatives></ref><ref id="cit44"><label>44</label><citation-alternatives><mixed-citation xml:lang="ru">Perelman G., A remark on soliton-potential interaction for nonlinear Schr¨odinger equations // Math. Res. Lett. — 2009. — V. 16(3). — P. 477-486.</mixed-citation><mixed-citation xml:lang="en">Perelman G., A remark on soliton-potential interaction for nonlinear Schr¨odinger equations // Math. Res. Lett. — 2009. — V. 16(3). — P. 477-486.</mixed-citation></citation-alternatives></ref><ref id="cit45"><label>45</label><citation-alternatives><mixed-citation xml:lang="ru">Pitaevskii L., Stringari S. Bose-Einstein condensation. — Oxford University Press, 2003.</mixed-citation><mixed-citation xml:lang="en">Pitaevskii L., Stringari S. Bose-Einstein condensation. — Oxford University Press, 2003.</mixed-citation></citation-alternatives></ref><ref id="cit46"><label>46</label><citation-alternatives><mixed-citation xml:lang="ru">Sacchetti A. Universal Critical Power for Nonlinear Schr¨odinger Equations with a Symmetric Double Well Potential // Phys. Rev. Lett. — 2009. — V. 103. — 194101.</mixed-citation><mixed-citation xml:lang="en">Sacchetti A. Universal Critical Power for Nonlinear Schr¨odinger Equations with a Symmetric Double Well Potential // Phys. Rev. Lett. — 2009. — V. 103. — 194101.</mixed-citation></citation-alternatives></ref><ref id="cit47"><label>47</label><citation-alternatives><mixed-citation xml:lang="ru">M. G. Vakhitov, A. A. Kolokolov: Stationary solutions of the wave equation in a medium with nonlinearity saturation // Radiophys. Quantum Electron. — 1973. — V. 16. — P. 783–789.</mixed-citation><mixed-citation xml:lang="en">M. G. Vakhitov, A. A. Kolokolov: Stationary solutions of the wave equation in a medium with nonlinearity saturation // Radiophys. Quantum Electron. — 1973. — V. 16. — P. 783–789.</mixed-citation></citation-alternatives></ref><ref id="cit48"><label>48</label><citation-alternatives><mixed-citation xml:lang="ru">Weinstein M.: Nonlinear Schr¨odinger equations and sharp interpolation estimates // Comm. Math. Phys. — 1983. — V. 87. — P. 567-576.</mixed-citation><mixed-citation xml:lang="en">Weinstein M.: Nonlinear Schr¨odinger equations and sharp interpolation estimates // Comm. Math. Phys. — 1983. — V. 87. — P. 567-576.</mixed-citation></citation-alternatives></ref><ref id="cit49"><label>49</label><citation-alternatives><mixed-citation xml:lang="ru">Weinstein M. Modulational stability of ground states of nonlinear Schr¨odinger equations // SIAM J. Math. Anal. — 1985. — V. 16. — P. 472-491.</mixed-citation><mixed-citation xml:lang="en">Weinstein M. Modulational stability of ground states of nonlinear Schr¨odinger equations // SIAM J. Math. Anal. — 1985. — V. 16. — P. 472-491.</mixed-citation></citation-alternatives></ref><ref id="cit50"><label>50</label><citation-alternatives><mixed-citation xml:lang="ru">Weinstein M.: Lyapunov stability of ground states of nonlinear dispersive evolution equations // Comm. Pure Appl. Math. — 1986. — V. 39. — P. 51–68.</mixed-citation><mixed-citation xml:lang="en">Weinstein M.: Lyapunov stability of ground states of nonlinear dispersive evolution equations // Comm. Pure Appl. Math. — 1986. — V. 39. — P. 51–68.</mixed-citation></citation-alternatives></ref></ref-list><fn-group><fn fn-type="conflict"><p>The authors declare that there are no conflicts of interest present.</p></fn></fn-group></back></article>
