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<div>Dear QE developers,</div><div><br></div><div>Recently, I calculate the phonon band of graphene by QE6.6. If the q point is 6x6x2, the result if fine. However, if the q point is 6x6x1, all the frequencies become their negative values (see the matdyn.freq.gp). </div><div><br></div><div>So, what is the problem? How to solve this question or how to improve the input files for the case of 6x6x1 calculations?</div><div><br></div><div>Thank you so much. I look forward to your reply.</div><div><br></div><div>Best ragards,</div><div><br></div><div>J.B. Liao</div><div><span style="line-height: 22.4px;">Henan Normal University</span></div>
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