<html><head><style type="text/css"><!-- DIV {margin:0px;} --></style></head><body><div style="font-family:Courier New,courier,monaco,monospace,sans-serif;font-size:12pt"><span id="result_box" class="long_text"><span style="" title="">Hello, Guda. </span><span style="" title="">The
errors in the determination of lattice parameters (a, b, c, alpha, beta
and gamma) are 1.5%, 0.9%, 1.6%, 0.7%, 0.04% and 2.1%, respectively. </span><span title="">But
the problem is that the value found for the alpha angle is slightly
lower than the experimental value despite being GGA functional. </span><span title="">In this case, all or not should not be overestimated?<br><br></span></span>Sincerely,<br><br>A. S. Santos<span style="text-decoration: underline;"><br></span><div>Univesidade Federal Fluminense<br>Niterói-Rio de Janeiro-Brasil <br></div><div><br></div><br><div> </div><div><br></div><div style="font-family: Courier New,courier,monaco,monospace,sans-serif; font-size: 12pt;"><br><div style="font-family: times new roman,new york,times,serif; font-size: 12pt;"><font face="Tahoma" size="2"><hr size="1"><b><span style="font-weight: bold;">De:</span></b> Guda Karthik <karthik.guda@gmail.com><br><b><span style="font-weight: bold;">Para:</span></b> PWSCF Forum <pw_forum@pwscf.org><br><b><span style="font-weight: bold;">Enviadas:</span></b> Terça-feira, 24 de Agosto de 2010 13:57:17<br><b><span style="font-weight: bold;">Assunto:</span></b> Re: [Pw_forum]
vc-relax, GGA<br></font><br>GGA results tend to overestimate the lattice parameters where as LDA results tend to underestimate the lattice parameters. Check how much is the error% in your DFT calculations.<br><br>regards,<br><br><div class="gmail_quote">
On Tue, Aug 24, 2010 at 12:35 PM, Álvaro Alves <span dir="ltr"><<a rel="nofollow" ymailto="mailto:asafis@yahoo.com.br" target="_blank" href="mailto:asafis@yahoo.com.br">asafis@yahoo.com.br</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
<div><div style="font-family: Courier New,courier,monaco,monospace,sans-serif; font-size: 12pt; color: rgb(0, 0, 0);"><span><span title="">Hello PWscf users. </span><span title="">I optimize a triclinic cell using the vc-relax, GGA functional. </span><span style="background-color: rgb(255, 255, 255);" title="">My expectation was that all values of the calculated parameters were slightly higher than the respective experimental values. </span><span style="background-color: rgb(255, 255, 255);" title="">But, the angle alpha showed a value slightly lower. </span><span style="background-color: rgb(255, 255, 255);" title="">The experimental value is in degree, 103.32, the calculated value is 102.6. </span><span title="">There is some inconsistency in this result?<br>
<br></span></span>Sincerely,<br>A. S. Santos<span style="text-decoration: underline;"><br></span><div>Univesidade Federal Fluminense<br>Niterói-Rio de Janeiro-Brasil <br></div><div><br></div>
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<br></blockquote></div><br><br clear="all"><br>-- <br>Karthik Guda<br>Graduate Student<br>Materials Engineering<br>Purdue University<br><br>
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