[Pw_forum] Only the rotation mode has imaginary frequency in 1 dimensional system

[Peng Tao]

Dear all,

I calculated the phonon dispersion curve of one-dimensional system, finding that
only rotational mode has imaginary frequency(about 180cm^-1). The frequencies are
not located on gamma point. Could anyone tell me what does it mean? I make sure 
that my calculation reached good convergence with extremely large Ecutrho and K 
mesh. Thank you very much.


Best regards,
Peng Tao


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PH.D. candidate Peng Tao 
Magnetism and Magnetic Materials Division
National Laboratory for Material Science
Institute of Metal Research, Chinese Academy of Sciences
Phone  +86-024-83978751
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