[QE-users] imaginary frequency reported for fixed atoms by ph.x

[兵临城下]

Dear all,


To save CPU time, we fixed atoms of the surface slab in the adsorption model during the PHONON calculation.


the input file are as follows,


WMC-1.0
&INPUTPH
   outdir='/fs08/home/js_wjliu/espresso-6.1/qe-6.1/tempdir/WMC-1.0-half-gamma/' ,
   prefix='WMC-1.0-half-gamma',
   fildyn='WMC-1.0-half-gamma.dynG',
   nat_todo=3
      nogg = .true.,
alpha_mix(1) = 0.1,
/
0.0 0.0 0.0
49 50 51



So we think only the frequency 145-153 corresponds to atom 49-51 would be reported.


However, we find the freq 1-9, which are 9 IMAGINARY frequencies  also reported by PHONON. 


Here are some information extracted from output file.




Mode symmetry, C_1 (1)     point group:




     Atomic displacements:
     There are 153 irreducible representations


     Representation     1      1 modes -A  Not done in this run


     Representation     2      1 modes -A  Not done in this run


     Representation     3      1 modes -A  Not done in this run


     Representation     4      1 modes -A  Not done in this run


     Representation     5      1 modes -A  Not done in this run


     Representation     6      1 modes -A  Not done in this run


     Representation     7      1 modes -A  Not done in this run


     Representation     8      1 modes -A  Not done in this run


     Representation     9      1 modes -A  Not done in this run


     Representation    10      1 modes -A  Not done in this run



     Representation   144      1 modes -A  Not done in this run


     Representation   145      1 modes -A  To be done


     Representation   146      1 modes -A  To be done


     Representation   147      1 modes -A  To be done


     Representation   148      1 modes -A  To be done


     Representation   149      1 modes -A  To be done


     Representation   150      1 modes -A  To be done


     Representation   151      1 modes -A  To be done


     Representation   152      1 modes -A  To be done


     Representation   153      1 modes -A  To be done


     Compute atoms:    49,   50,   51,



     Alpha used in Ewald sum =   2.8000


     negative rho (up, down):  9.406E-05 3.627E-03
     PHONON       :     1h22m CPU       22h 1m WALL







     Mode symmetry, C_1 (1)     point group:


     freq (  1 -  1) =      -1086.5  [cm-1]   --> A               I+R
     freq (  2 -  2) =       -815.1  [cm-1]   --> A               I+R
     freq (  3 -  3) =       -764.6  [cm-1]   --> A               I+R
     freq (  4 -  4) =       -458.8  [cm-1]   --> A               I+R
     freq (  5 -  5) =       -240.8  [cm-1]   --> A               I+R
     freq (  6 -  6) =       -206.1  [cm-1]   --> A               I+R
     freq (  7 -  7) =       -127.7  [cm-1]   --> A               I+R
     freq (  8 -  8) =        -59.4  [cm-1]   --> A               I+R
     freq (  9 -  9) =        -21.3  [cm-1]   --> A               I+R
     freq (145 -145) =        255.2  [cm-1]   --> A               I+R
     freq (146 -146) =        438.0  [cm-1]   --> A               I+R
     freq (147 -147) =        507.2  [cm-1]   --> A               I+R
     freq (148 -148) =        681.1  [cm-1]   --> A               I+R
     freq (149 -149) =        810.3  [cm-1]   --> A               I+R
     freq (150 -150) =       1124.5  [cm-1]   --> A               I+R
     freq (151 -151) =       1568.3  [cm-1]   --> A               I+R
     freq (152 -152) =       3534.8  [cm-1]   --> A               I+R
     freq (153 -153) =       3559.3  [cm-1]   --> A               I+R



We also find although we input a unstable adsorption configuration for atom 49-51, there is no imaginary frequency reported in freq 145-153.


Could anyone help us to deal with this problem. Thanks in advance.


best wishes


vega
------------------
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vega
Department of physics, Nanjing University, China
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