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<div style="direction: ltr;font-family: Tahoma;color: #000000;font-size: 10pt;">Dear QE users,
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<div>I'm using QE/5.0.3 to calculate the phonon dispersion curve of BaF2. I would like to relax the structure so I started the calculation with 'vc-relax' followed by ph.x calculation. Then to obtain the interatomic force constant, I used q2r.x routine, but
 I got the error message:</div>
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<pre>><i>%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
</i>>><i>      from init : error #         1
</i>>><i>      q not allowed
</i>>><i>
</i>>><i>%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%</i></pre>
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<div><font face="Tahoma" style="font-size: 10pt;">I thing the reason for this is the incompatibility of
</font><span style="font-size: 10pt;">q-mesh generated by ph.x and q2r.x as pointed out by
</span><span style="font-size: 10pt;">Prof. Eyvaz Isaev in his post </span><span style="font-size: 10pt;">dated back to August 4 2010. However, he didn't mention how to fix this problem. Does anyone have any idea? Any suggestion or </span><span style="font-size: 10pt;">help
 would be greatly appreciated.</span></div>
<div><span style="font-size: 10pt;">Thank you in advance for your help.</span></div>
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<div><span style="font-size: 10pt;">Sokseiha Muy,</span></div>
<div>Electrochemical Energy Laboratory,</div>
<div>Department of Materials Science and Engineering, MIT.</div>
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