<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
<style type="text/css" style="display:none;"> P {margin-top:0;margin-bottom:0;} </style>
</head>
<body dir="ltr">
<div style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
Dear all</div>
<div style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
<br>
</div>
<div style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
I'm having some difficulties to work with the TB09 functional. After some reading, I found in some old posts that this can be done by compiling QE with Libxc, and by adding the line 'input_dft='tb09'' in the pw.x input.</div>
<div style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
<br>
</div>
<div style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
When I try to use this functional, the scf calculation always ends like this:</div>
<div style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
<br>
</div>
<div style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
total energy = NaN Ry Harris-Foulkes estimate = -11.24358313 Ry estimated scf accuracy < 0.01858366 Ry iteration # 18 ecut= 120.00 Ry beta= 0.10 Davidson diagonalization with overlap %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
Error in routine cdiaghg (7): eigenvectors failed to converge %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%<br>
</div>
<div style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
<br>
</div>
<div style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
<span style="color: rgb(0, 0, 0); font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; background: var(--white);">What draws my attention is that always in the last cycle before the error the total energy is printed as NaN. The parameters to the calculation
seem to be fine, as it ends smoothly without the input_dft line.</span><br>
</div>
<div style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
<br>
</div>
<div><font color="#000000" face="Calibri, Helvetica, sans-serif" size="3">By searching in the QE user guide, there is a reference to the work of E. Germaneau, which lead me to his paper
<font color="#000000" face="Calibri, Helvetica, sans-serif"><font size="3"><span style="font-size: 12pt; line-height: normal;">(</span></font></font><span style="margin: 0px; font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(136, 136, 136); caret-color: rgb(136, 136, 136); text-align: left; display: inline !important; line-height: normal;">DOI:</span><span style="margin: 0px; font-family: Roboto, Arial, sans-serif; font-size: 12px; color: rgb(136, 136, 136); caret-color: rgb(136, 136, 136); text-align: left; display: inline !important;"><span style="margin: 0px; font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; line-height: normal;"> </span></span><span style="margin: 0px; font-family: Calibri, Helvetica, sans-serif; font-size: 12px; outline: none; background-image: none; text-align: left; display: inline; cursor: pointer; caret-color: rgb(136, 136, 136);"><a href="http://dx.doi.org/10.1016/j.cpc.2013.02.020" target="_blank" rel="noopener" style="margin: 0px; font-family: Roboto, Arial, sans-serif; outline: none; background-image: none; display: inline; caret-color: rgb(136, 136, 136);"><span style="font-size: 12pt; line-height: normal;">10.1016/j.cpc.2013.02.020</span></a></span><span style="margin: 0px; font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; outline: none; background-image: none; text-align: left; display: inline; cursor: pointer; caret-color: rgb(136, 136, 136); line-height: normal;">)</span>,
where the results of his implementation are presented. Even </font><font color="#000000" face="Calibri, Helvetica, sans-serif"><span style="caret-color: rgb(0, 0, 0);">though, it is unclear to me how to use the functional </span></font><font color="#000000" face="Calibri, Helvetica, sans-serif">correctly.<font size="3"> </font></font></div>
<div><br>
</div>
<div><font color="#000000" face="Calibri, Helvetica, sans-serif" size="3"><span style="caret-color: rgb(0, 0, 0);">Thanks for any assistance</span></font></div>
<div><font color="#000000" face="Calibri, Helvetica, sans-serif" size="3"><span style="caret-color: rgb(0, 0, 0);">Fábio Costa</span></font></div>
</body>
</html>