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--></style></head><body lang=EN-US link=blue vlink="#954F72"><div class=WordSection1><p class=MsoNormal>Dear Prof. Paolo Giannozzi, </p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>The threshold of convergence is 10^-17 in phonon calculation. I checked that if the threshold convergence is 10^-15, it is the same case that the symmetry of the two-fold frequencies could not be determined. However, if the convergence threshold is smaller, I would get imaginary frequencies even after applying ASR. <o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Best regards<o:p></o:p></p><p class=MsoNormal>Zhishuo Huang<o:p></o:p></p></div></body></html>