<?xml version="1.0" encoding="ISO-8859-1"?><article 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">
<front>
<journal-meta>
<journal-id>0035-001X</journal-id>
<journal-title><![CDATA[Revista mexicana de física]]></journal-title>
<abbrev-journal-title><![CDATA[Rev. mex. fis.]]></abbrev-journal-title>
<issn>0035-001X</issn>
<publisher>
<publisher-name><![CDATA[Sociedad Mexicana de Física]]></publisher-name>
</publisher>
</journal-meta>
<article-meta>
<article-id>S0035-001X2003000300003</article-id>
<title-group>
<article-title xml:lang="en"><![CDATA[Two-particle correlations in the one-dimensional Hubbard model: a ground-state analytical solution]]></article-title>
</title-group>
<contrib-group>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Vallejo]]></surname>
<given-names><![CDATA[E.]]></given-names>
</name>
<xref ref-type="aff" rid="A01"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Navarro]]></surname>
<given-names><![CDATA[O.]]></given-names>
</name>
<xref ref-type="aff" rid="A01"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Espinosa]]></surname>
<given-names><![CDATA[J.E.]]></given-names>
</name>
<xref ref-type="aff" rid="A01"/>
</contrib>
</contrib-group>
<aff id="A01">
<institution><![CDATA[,Universidad Nacional Autónoma de México Instituto de Investigaciones en Materiales ]]></institution>
<addr-line><![CDATA[México Distrito Federal]]></addr-line>
<country>México</country>
</aff>
<aff id="A02">
<institution><![CDATA[,Benemérita Universidad Autónoma de Puebla Facultad de Ciencias Físico-Matemáticas Posgrado en Optoelectrónica]]></institution>
<addr-line><![CDATA[Puebla ]]></addr-line>
<country>México</country>
</aff>
<pub-date pub-type="pub">
<day>00</day>
<month>00</month>
<year>2003</year>
</pub-date>
<pub-date pub-type="epub">
<day>00</day>
<month>00</month>
<year>2003</year>
</pub-date>
<volume>49</volume>
<numero>3</numero>
<fpage>207</fpage>
<lpage>211</lpage>
<copyright-statement/>
<copyright-year/>
<self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_arttext&amp;pid=S0035-001X2003000300003&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_abstract&amp;pid=S0035-001X2003000300003&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_pdf&amp;pid=S0035-001X2003000300003&amp;lng=en&amp;nrm=iso"></self-uri><abstract abstract-type="short" xml:lang="en"><p><![CDATA[A solution to the extended Hubbard Hamiltonian for the case of two-particles in an infinite one-dimensional lattice is presented, using a real-space mapping method and the Green function technique. This Hamiltonian considers the on-site (U) and the nearest-neighbor (V) interactions. The method is based on mapping the correlated many-body problem onto an equivalent site-impurity tight-binding one in a higher dimensional space. In this new space we obtained the analytical solution for the ground state binding energy. Results are in agreement with the numerical solution obtained previously [1], and with those obtained in the reciprocal space [2].]]></p></abstract>
<abstract abstract-type="short" xml:lang="es"><p><![CDATA[Se resolvió el hamiltoniano de Hubbard extendido para dos partículas en una red unidimensional, usando el método del mapeo en el espacio real y la técnica de la función de Green. Este hamiltoniano considera las interacciones intra-atómicas U e inter-atómicas V. El método mapea el problema de muchos cuerpos correlación de un problema equivalente de amarre fuerte en un espacio de mayor dimensión. Haciendo un análisis del problema en este espacio se obtuvo la solución analítica para la energía de enlace del estado base. Los resultados están en completo acuerdo con la soluciones obtenidas tanto numéricamente [1] como en el espacio recíproco [2].]]></p></abstract>
<kwd-group>
<kwd lng="en"><![CDATA[Hubbard model]]></kwd>
<kwd lng="en"><![CDATA[fermions in reduced dimensions]]></kwd>
<kwd lng="en"><![CDATA[strongly correlated electron systems]]></kwd>
<kwd lng="es"><![CDATA[Modelo de Hubbard]]></kwd>
<kwd lng="es"><![CDATA[fermiones en dimensiones reducidas]]></kwd>
<kwd lng="es"><![CDATA[sistemas electrónicos fuertemente correlacionados]]></kwd>
</kwd-group>
</article-meta>
</front><body><![CDATA[ <p align="justify"><font face="verdana" size="4">Investigaci&oacute;n</font></p>     <p align="justify">&nbsp;</p>  	    <p align="center"><font face="verdana" size="4"><b>Two&#45;particle correlations in the one&#45;dimensional Hubbard model: a ground&#45;state analytical solution</b></font></p>     <p align="center">&nbsp;</p>              <p align="center"><font face="verdana" size="2"><b>E. Vallejo<sup>1</sup>, O. Navarro<sup>1</sup>, J.E. Espinosa<sup>2</sup></b></font></p>         <p align="center">&nbsp;</p>              <p align="justify"><font face="verdana" size="2"><sup><i>1</i></sup> <i>Instituto de Investigaciones en Materiales, Universidad Nacional Aut&oacute;noma de M&eacute;xico, Apartado Postal 70&#45;360, 04510 M&eacute;xico D.F., M&eacute;xico.</i></font></p>             <p align="justify"><font face="verdana" size="2"><sup><i>2</i></sup> <i>Facultad de Ciencias F&iacute;sico&#45;Matem&aacute;ticas (Posgrado en Optoelectr&oacute;nica) BUAP,</i> <i>Puebla Pue., M&eacute;xico.</i></font></p>        <p align="justify">&nbsp;</p>            <p align="justify"><font face="verdana" size="2">Recibido el 29 de abril de 2002.     ]]></body>
<body><![CDATA[<br> Aceptado el 27 de noviembre de 2002.</font></p>      <p align="justify">&nbsp;</p>     <p align="justify"><font face="verdana" size="2"><b>Abstract</b></font></p>      <p align="justify"><font face="verdana" size="2">A solution to the extended Hubbard Hamiltonian for the case of two&#45;particles in an infinite one&#45;dimensional lattice is presented, using a real&#45;space mapping method and the Green function technique. This Hamiltonian considers the on&#45;site (<i>U</i>) and the nearest&#45;neighbor (<i>V</i>) interactions. The method is based on mapping the correlated many&#45;body problem onto an equivalent site&#45;impurity tight&#45;binding one in a higher dimensional space. In this new space we obtained the analytical solution for the ground state binding energy. Results are in agreement with the numerical solution obtained previously &#91;1&#93;, and with those obtained in the reciprocal space &#91;2&#93;.</font></p>      <p align="justify"><font face="verdana" size="2"><b>Keywords:</b> Hubbard model, fermions in reduced dimensions, strongly correlated electron systems.</font></p>      <p align="justify">&nbsp;</p>     <p align="justify"><font face="verdana" size="2"><b>Resumen</b></font></p>      <p align="justify"><font face="verdana" size="2">Se resolvi&oacute; el hamiltoniano de Hubbard extendido para dos part&iacute;culas en una red unidimensional, usando el m&eacute;todo del mapeo en el espacio real y la t&eacute;cnica de la funci&oacute;n de Green. Este hamiltoniano considera las interacciones intra&#45;at&oacute;micas <i>U</i> e inter&#45;at&oacute;micas <i>V</i>. El m&eacute;todo mapea el problema de muchos cuerpos correlaci&oacute;n de un problema equivalente de amarre fuerte en un espacio de mayor dimensi&oacute;n. Haciendo un an&aacute;lisis del problema en este espacio se obtuvo la soluci&oacute;n anal&iacute;tica para la energ&iacute;a de enlace del estado base. Los resultados est&aacute;n en completo acuerdo con la soluciones obtenidas tanto num&eacute;ricamente &#91;1&#93; como en el espacio rec&iacute;proco &#91;2&#93;.</font></p>      <p align="justify"><font face="verdana" size="2"><b>Palabras clave:</b> Modelo de Hubbard, fermiones en dimensiones reducidas, sistemas electr&oacute;nicos fuertemente correlacionados.</font></p>      <p align="justify"><font face="verdana" size="2">PACS: 71.10.fd; 71.10Pm; 71.10Li; 71.27.+a</font></p>      ]]></body>
<body><![CDATA[<p align="justify">&nbsp;</p>     <p align="justify"><font face="verdana" size="2"><a href="/pdf/rmf/v49n3/v49n3a3.pdf" target="_blank">DESCARGAR ART&Iacute;CULO EN FORMATO PDF</a></font></p>      <p align="justify">&nbsp;</p>     <p align="justify"><font face="verdana" size="2"><b>Acknowledgement</b></font></p>      <p align="justify"><font face="verdana" size="2">This work was partially supported by grants from CONACyT M&eacute;xico 33630&#45;E, from UNAM through IN106600 and by DGEP&#45;UNAM.</font></p>      <p align="justify">&nbsp;</p>     <p align="justify"><font face="verdana" size="2"><b>References</b></font></p>     <!-- ref --><p align="justify"><font face="verdana" size="2">1. O. Navarro and C. Wang, <i>Rev. Mex. 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