<?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>S0035-001X2012000100003</article-id>
<title-group>
<article-title xml:lang="en"><![CDATA[Algorithm to compute the electric field gradient tensor in ionic crystals]]></article-title>
</title-group>
<contrib-group>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Hernández-Gómez]]></surname>
<given-names><![CDATA[J.J.]]></given-names>
</name>
<xref ref-type="aff" rid="A01"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Marquina]]></surname>
<given-names><![CDATA[V]]></given-names>
</name>
<xref ref-type="aff" rid="A01"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Gómez]]></surname>
<given-names><![CDATA[R.W.]]></given-names>
</name>
<xref ref-type="aff" rid="A01"/>
</contrib>
</contrib-group>
<aff id="A01">
<institution><![CDATA[,Universidad Nacional Autónoma de México Facultad de Ciencias ]]></institution>
<addr-line><![CDATA[México D.F.]]></addr-line>
<country>México</country>
</aff>
<pub-date pub-type="pub">
<day>00</day>
<month>02</month>
<year>2012</year>
</pub-date>
<pub-date pub-type="epub">
<day>00</day>
<month>02</month>
<year>2012</year>
</pub-date>
<volume>58</volume>
<numero>1</numero>
<fpage>13</fpage>
<lpage>18</lpage>
<copyright-statement/>
<copyright-year/>
<self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_arttext&amp;pid=S0035-001X2012000100003&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_abstract&amp;pid=S0035-001X2012000100003&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_pdf&amp;pid=S0035-001X2012000100003&amp;lng=en&amp;nrm=iso"></self-uri><abstract abstract-type="short" xml:lang="en"><p><![CDATA[A simple algorithm and a computational program to numerically compute the electric field gradient and the concomitant quadrupolar nuclear splitting is developed for an arbitrary ionic crystal. The calculations are performed using a point charge model. The program provides three different ways for the data input: by Bravais lattices, by lattice parameters, or by introducing any spatial structure. The program calculates the components of the electric field gradient, the asymmetry parameter and the quadrupolar splitting for a given number of nearest neighbors with respect to the nuclear charge as origin. In addition, the program allows the use of different Sternheimer antishielding factors.]]></p></abstract>
<kwd-group>
<kwd lng="en"><![CDATA[Electric field gradient]]></kwd>
<kwd lng="en"><![CDATA[quadrupolar splitting]]></kwd>
<kwd lng="en"><![CDATA[Mossbauer spectroscopy]]></kwd>
<kwd lng="en"><![CDATA[algorithm and numerical computation]]></kwd>
<kwd lng="en"><![CDATA[asymmetry parameter]]></kwd>
<kwd lng="en"><![CDATA[crystallographic lattices]]></kwd>
</kwd-group>
</article-meta>
</front><body><![CDATA[ <p align="justify"><font face="verdana" size="4">Investigaci&oacute;n</font></p>     <p align="justify"><font face="verdana" size="4">&nbsp;</font></p>     <p align="center"><font face="verdana" size="4"><b>Algorithm to compute the electric field gradient tensor in ionic crystals</b></font></p>     <p align="center"><font face="verdana" size="2">&nbsp;</font></p>     <p align="center"><font face="verdana" size="2"><b>J.J. Hern&aacute;ndez&#150;G&oacute;mez, V. Marquina and R.W. G&oacute;mez</b></font></p>     <p align="justify"><font face="verdana" size="2">&nbsp;</font></p>     <p align="justify"><font face="verdana" size="2"><i>Facultad de Ciencias, Universidad Nacional Aut&oacute;noma de M&eacute;xico Circuito Exterior, Ciudad Universitaria, D.F., M&eacute;xico, 04510, M&eacute;xico.</i></font></p>     <p align="justify"><font face="verdana" size="2">&nbsp;</font></p>     <p align="justify"><font face="verdana" size="2">Recibido el 19 de septiembre de 2011.    <br> Aceptado el 25 de noviembre de 2011.</font></p>     ]]></body>
<body><![CDATA[<p align="justify"><font face="verdana" size="2">&nbsp;</font></p>     <p align="justify"><font face="verdana" size="2"><b>Abstract</b></font></p>     <p align="justify"><font face="verdana" size="2">A simple algorithm and a computational program to numerically compute the electric field gradient and the concomitant quadrupolar nuclear splitting is developed for an arbitrary ionic crystal. The calculations are performed using a point charge model. The program provides three different ways for the data input: by Bravais lattices, by lattice parameters, or by introducing any spatial structure. The program calculates the components of the electric field gradient, the asymmetry parameter and the quadrupolar splitting for a given number of nearest neighbors with respect to the nuclear charge as origin. In addition, the program allows the use of different Sternheimer antishielding factors.</font></p>     <p align="justify"><font face="verdana" size="2"><b>Keywords: </b>Electric field gradient; quadrupolar splitting; Mossbauer spectroscopy; algorithm and numerical computation; asymmetry parameter; crystallographic lattices.</font></p>     <p align="justify"><font face="verdana" size="2">&nbsp;</font></p>     <p align="justify"><font face="verdana" size="2">PACS: 61.18.Fs; 76.60.Gv; 76.80.Ay</font></p>     <p align="justify"><font face="verdana" size="2">&nbsp;</font></p>     <p align="justify"><font face="verdana" size="2"><a href="/pdf/rmf/v58n1/v58n1a3.pdf" target="_blank">DESCARGAR ART&Iacute;CULO EN FORMATO PDF</a></font></p>     <p align="justify"><font face="verdana" size="2">&nbsp;</font></p>     <p align="justify"><font face="verdana" size="2"><b>Acknowledgements</b></font></p>     ]]></body>
<body><![CDATA[<p align="justify"><font face="verdana" size="2">This work was partially supported by DGAPA&#150;UNAM IN115612 grant.</font></p>     <p align="justify"><font face="verdana" size="2">&nbsp;</font></p>     <p align="justify"><font face="verdana" size="2"><b>Note</b></font></p>     <p align="justify"><font face="verdana" size="2">The program is available for its free usage under request, if and only if the appropriate acknowledgement and credit is given to the authors.</font></p>     <p align="justify"><font face="verdana" size="2">&nbsp;</font></p>     <p align="justify"><font face="verdana" size="2"><b><a href="/img/revistas/rmf/v58n1/html/a3apendice1.htm" target="_blank">Appendix</a></b></font></p>     <p align="justify"><font face="verdana" size="2">&nbsp;</font></p>     <p align="justify"><font face="verdana" size="2"><b>References</b></font></p>     <!-- ref --><p align="justify"><font face="verdana" size="2">1. Blatt&#150;Weisskopf, <i>Theoretical Nuclear Physics, </i>7th print, (Wiley, New York, 1963).    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[&#160;<a href="javascript:void(0);" onclick="javascript: window.open('/scielo.php?script=sci_nlinks&ref=8375765&pid=S0035-001X201200010000300001&lng=','','width=640,height=500,resizable=yes,scrollbars=1,menubar=yes,');">Links</a>&#160;]<!-- end-ref --></font></p>     ]]></body>
<body><![CDATA[<!-- ref --><p align="justify"><font face="verdana" size="2">2. B.D. Dunlop, <i>Mossbauer Effect Data Index, </i>Appendix I: An Introduction to Electric Quadrupole Interactions in Mossbauer Spectroscopy, (Plenum Press, I&#150;T&#150;I, 1970).    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[&#160;<a href="javascript:void(0);" onclick="javascript: window.open('/scielo.php?script=sci_nlinks&ref=8375767&pid=S0035-001X201200010000300002&lng=','','width=640,height=500,resizable=yes,scrollbars=1,menubar=yes,');">Links</a>&#160;]<!-- end-ref --></font></p>     <!-- ref --><p align="justify"><font face="verdana" size="2">3. J.D. Jackson, <i>Classical Electrodynamics, </i>3rd ed. (Wiley, 1998).    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[&#160;<a href="javascript:void(0);" onclick="javascript: window.open('/scielo.php?script=sci_nlinks&ref=8375769&pid=S0035-001X201200010000300003&lng=','','width=640,height=500,resizable=yes,scrollbars=1,menubar=yes,');">Links</a>&#160;]<!-- end-ref --></font></p>     <!-- ref --><p align="justify"><font face="verdana" size="2">4. A. Messiah, <i>Quantum Mechanics </i>Two Volumes Bound as One. (Dover Publications Inc., New York, 1962), pp. 573.    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[&#160;<a href="javascript:void(0);" onclick="javascript: window.open('/scielo.php?script=sci_nlinks&ref=8375771&pid=S0035-001X201200010000300004&lng=','','width=640,height=500,resizable=yes,scrollbars=1,menubar=yes,');">Links</a>&#160;]<!-- end-ref --></font></p>     <!-- ref --><p align="justify"><font face="verdana" size="2">5. H. Fraunfelder, <i>The Mossbauer Effect, </i>(W.A. Benjamin Inc., New York, 1962).    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[&#160;<a href="javascript:void(0);" onclick="javascript: window.open('/scielo.php?script=sci_nlinks&ref=8375773&pid=S0035-001X201200010000300005&lng=','','width=640,height=500,resizable=yes,scrollbars=1,menubar=yes,');">Links</a>&#160;]<!-- end-ref --></font></p>     <!-- ref --><p align="justify"><font face="verdana" size="2">6. N.N. Greenwood, T.C. Gibb., <i>Mossbauer Spectroscopy, </i>(Chapman and Hall Ltd., London, 1971).    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[&#160;<a href="javascript:void(0);" onclick="javascript: window.open('/scielo.php?script=sci_nlinks&ref=8375775&pid=S0035-001X201200010000300006&lng=','','width=640,height=500,resizable=yes,scrollbars=1,menubar=yes,');">Links</a>&#160;]<!-- end-ref --></font></p>     ]]></body>
<body><![CDATA[<!-- ref --><p align="justify"><font face="verdana" size="2">7. R.M. Sternheimer, <i>Phys. Rev. </i><b>80 </b>(1950) 102.    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[&#160;<a href="javascript:void(0);" onclick="javascript: window.open('/scielo.php?script=sci_nlinks&ref=8375777&pid=S0035-001X201200010000300007&lng=','','width=640,height=500,resizable=yes,scrollbars=1,menubar=yes,');">Links</a>&#160;]<!-- end-ref --></font></p>     <!-- ref --><p align="justify"><font face="verdana" size="2">8. R.M. Sternheimer, <i>Phys. Rev. </i><b>84 </b>(1951) 244.    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[&#160;<a href="javascript:void(0);" onclick="javascript: window.open('/scielo.php?script=sci_nlinks&ref=8375779&pid=S0035-001X201200010000300008&lng=','','width=640,height=500,resizable=yes,scrollbars=1,menubar=yes,');">Links</a>&#160;]<!-- end-ref --></font></p>     <!-- ref --><p align="justify"><font face="verdana" size="2">9. R.M. Sternheimer, <i>Phys. Rev. </i><b>132 </b>(1963) 1637.    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[&#160;<a href="javascript:void(0);" onclick="javascript: window.open('/scielo.php?script=sci_nlinks&ref=8375781&pid=S0035-001X201200010000300009&lng=','','width=640,height=500,resizable=yes,scrollbars=1,menubar=yes,');">Links</a>&#160;]<!-- end-ref --></font></p>     <!-- ref --><p align="justify"><font face="verdana" size="2">10. R.M. Sternheimer, <i>Phys. Rev. </i><b>164 </b>(1967) 10.    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[&#160;<a href="javascript:void(0);" onclick="javascript: window.open('/scielo.php?script=sci_nlinks&ref=8375783&pid=S0035-001X201200010000300010&lng=','','width=640,height=500,resizable=yes,scrollbars=1,menubar=yes,');">Links</a>&#160;]<!-- end-ref --></font></p>     <!-- ref --><p align="justify"><font face="verdana" size="2">11. R.M. Sternheimer, <i>Phys. Rev. A. </i><b>6 </b>(1972) 1702.    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[&#160;<a href="javascript:void(0);" onclick="javascript: window.open('/scielo.php?script=sci_nlinks&ref=8375785&pid=S0035-001X201200010000300011&lng=','','width=640,height=500,resizable=yes,scrollbars=1,menubar=yes,');">Links</a>&#160;]<!-- end-ref --></font></p>     ]]></body>
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