[QE-users] Question on 2D materials'phonons

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Dear Espresso community

Recently , I am calculating 2D materials' phonons , but the output files named xx.dyn* always show imaginary frequency at Gamma point , particularly thefreq(1) that is negative about  "- 0.5 ~ -3 Thz" .I haved tried to increase K points , using different smearing methods and degauss (about 0.05) , but freq(1) in xxx.dyn1 is always a small negative value.So I can't calculate superconductor temperature.I wanted to ask how to eliminate imaginary frequency at Gamma point , particularly the negative freq(1)  in xxx.dyn1 files.
Thank you very much. With kind regards.
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