thank Paolo Giannozzi as well as L.F.Huang .<br><br>
<div class="gmail_quote">2009/12/21 Paolo Giannozzi <span dir="ltr"><<a href="mailto:giannozz@democritos.it">giannozz@democritos.it</a>></span><br>
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<div class="im">xu yuehua wrote:<br><br>> and is that theory used in PWSCF code?<br><br></div><a href="http://www.springer.com/physics/book/978-1-4020-3287-5" target="_blank">http://www.springer.com/physics/book/978-1-4020-3287-5</a><br>
go to 'Sample pages', download the file. It contains a brief<br>introduction to density-fgunctional perturbation theory,<br>including some essential info on how to calculate IR cross<br>sections<br><br>P.<br><font color="#888888">--<br>
Paolo Giannozzi, Democritos and University of Udine, Italy<br></font>
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<div class="h5">_______________________________________________<br>Pw_forum mailing list<br><a href="mailto:Pw_forum@pwscf.org">Pw_forum@pwscf.org</a><br><a href="http://www.democritos.it/mailman/listinfo/pw_forum" target="_blank">http://www.democritos.it/mailman/listinfo/pw_forum</a><br>
</div></div></blockquote></div><br><br clear="all"><br>-- <br>Yuehua Xu<br>Group of Computational Condensed Matter Physics, <br>National Laboratory of Solid State Microstructures and Department of Physics, <br>Nanjing University,<br>
Nanjing 210093,<br>P. R. China<br><br>