<br><br><div class="gmail_quote">On Sun, Apr 8, 2012 at 12:17 PM, henry odhiambo <span dir="ltr"><<a href="mailto:henod2001@yahoo.com">henod2001@yahoo.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<table cellspacing="0" cellpadding="0" border="0"><tbody><tr><td valign="top" style="font:inherit"><div>Hello colleagues,</div>
<div> </div>
<div>I am calculating the phonon frequencies for stable ( or hexagonal) GST (Ge2Sb2Te5). I am getting some negative values (contrary to the notion of stability and literature). I used the unrelaxed structure to do the calculations. Could this be the reason?</div>
</td></tr></tbody></table></blockquote><div><br></div><div>yes. check out how phonons are calculated</div><div>and then it will be evident why.</div><div><br></div><div>axel.</div><div><br></div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
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<div> </div>
<div>Henry Otunga</div>
<div>Dept. of Physics</div>
<div>Maseno UNiversity</div>
<div>Kenya </div></td></tr></tbody></table><br>_______________________________________________<br>
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<br></blockquote></div><br><br clear="all"><div><br></div>-- <br>Dr. Axel Kohlmeyer <br><a href="mailto:akohlmey@gmail.com" target="_blank">akohlmey@gmail.com</a> <a href="http://goo.gl/1wk0" target="_blank">http://goo.gl/1wk0</a><br>
<br>College of Science and Technology<br>Temple University, Philadelphia PA, USA.<br>