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<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 pub-id-type="doi">10.17586/2220-8054-2015-6-6-762-766</article-id><article-id custom-type="elpub" pub-id-type="custom">najo-889</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>PAPERS, PRESENTED AT THE CONFERENCE</subject></subj-group><subj-group subj-group-type="section-heading" xml:lang="ru"><subject>PAPERS, PRESENTED AT THE CONFERENCE</subject></subj-group></article-categories><title-group><article-title>The Green function for simplest quantum graphs</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>Sabirov</surname><given-names>K. K.</given-names></name></name-alternatives><bio xml:lang="en"><p>Tashkent </p></bio><email xlink:type="simple">karimjonsabirov@yahoo.com</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>Aminov</surname><given-names>U. A.</given-names></name></name-alternatives><bio xml:lang="en"><p>Urganch</p></bio><xref ref-type="aff" rid="aff-2"/></contrib><contrib contrib-type="author" corresp="yes"><name-alternatives><name name-style="western" xml:lang="en"><surname>Saparov</surname><given-names>Kh. Sh.</given-names></name></name-alternatives><bio xml:lang="en"><p>Urganch</p></bio><xref ref-type="aff" rid="aff-2"/></contrib><contrib contrib-type="author" corresp="yes"><name-alternatives><name name-style="western" xml:lang="en"><surname>Karimov</surname><given-names>M. K.</given-names></name></name-alternatives><bio xml:lang="en"><p>Urganch</p></bio><xref ref-type="aff" rid="aff-2"/></contrib><contrib contrib-type="author" corresp="yes"><name-alternatives><name name-style="western" xml:lang="en"><surname>Abdikarimov</surname><given-names>Kh.</given-names></name></name-alternatives><bio xml:lang="en"><p>Urganch</p></bio><xref ref-type="aff" rid="aff-2"/></contrib></contrib-group><aff xml:lang="en" id="aff-1"><institution>Physics Faculty, National University of Uzbekistan</institution><country>Uzbekistan</country></aff><aff xml:lang="en" id="aff-2"><institution>Urganch State University</institution><country>Uzbekistan</country></aff><pub-date pub-type="collection"><year>2015</year></pub-date><pub-date pub-type="epub"><day>15</day><month>08</month><year>2025</year></pub-date><volume>6</volume><issue>6</issue><fpage>762</fpage><lpage>766</lpage><permissions><copyright-statement>Copyright &amp;#x00A9; Sabirov K.K., Aminov U.A., Saparov K.S., Karimov M.K., Abdikarimov K., 2025</copyright-statement><copyright-year>2025</copyright-year><copyright-holder xml:lang="ru">Sabirov K.K., Aminov U.A., Saparov K.S., Karimov M.K., Abdikarimov K.</copyright-holder><copyright-holder xml:lang="en">Sabirov K.K., Aminov U.A., Saparov K.S., Karimov M.K., Abdikarimov K.</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/889">https://nanojournal.ifmo.ru/jour/article/view/889</self-uri><abstract><p>We treat the problem of the Green function for quantum graphs by focusing on such topologies as star and tree graphs. The exact Green function for the Schr¨odinger equation on primary star graphs is derived in the form of 3 × 3− matrix using the vertex boundary conditions providing continuity and current conservation. Extension of the approach for the derivation for the Green function on tree graph is presented. Possible practical applications of the obtained results are discussed.</p></abstract><kwd-group xml:lang="en"><kwd>quantum graphs</kwd><kwd>Green function</kwd><kwd>vertex boundary conditions</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">T. Kottos and U. Smilansky. Periodic orbit theory and spectral statistics for quantum graphs, Ann.Phys., 1999, 76, P. 274.</mixed-citation><mixed-citation xml:lang="en">T. Kottos and U. Smilansky. 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