# [Pw_forum] What's real imaginary frequency of the transition state?

Tue Jun 29 05:14:10 CEST 2010

```Hi, dear all,
There are always some imaginary frequencies in the output of ph.x, whether it is in the calculation of transition states or not. why? In searching transition states, there are also many imaginary frequencies in the output file,usually. I'm confused. How I can pick out the real imaginary frequency of the transition state? Below is an example of a part of transition state calculation output:
**************************************************************************
omega( 1) =      -6.576208 [THz] =    -219.360155 [cm-1]
omega( 2) =      -4.209028 [THz] =    -140.398981 [cm-1]
omega( 3) =      -2.230600 [THz] =     -74.405297 [cm-1]
omega( 4) =      -0.970684 [THz] =     -32.378747 [cm-1]
omega( 5) =      -0.867754 [THz] =     -28.945364 [cm-1]
omega( 6) =       1.971578 [THz] =      65.765185 [cm-1]
omega( 7) =       2.101039 [THz] =      70.083572 [cm-1]
omega( 8) =       2.527013 [THz] =      84.292637 [cm-1]
omega( 9) =       3.283256 [THz] =     109.518370 [cm-1]
omega(10) =       3.705495 [THz] =     123.602844 [cm-1]
omega(11) =       4.142298 [THz] =     138.173116 [cm-1]
omega(12) =       4.503254 [THz] =     150.213369 [cm-1]
omega(13) =       5.135967 [THz] =     171.318563 [cm-1]
omega(14) =       5.632122 [THz] =     187.868601 [cm-1]
omega(15) =       5.854701 [THz] =     195.293098 [cm-1]
omega(16) =       6.304154 [THz] =     210.285335 [cm-1]
omega(17) =       6.549402 [THz] =     218.465998 [cm-1]
omega(18) =       7.221822 [THz] =     240.895661 [cm-1]
omega(19) =       7.319292 [THz] =     244.146926 [cm-1]
omega(20) =       7.657549 [THz] =     255.430048 [cm-1]
omega(21) =       7.695989 [THz] =     256.712278 [cm-1]
omega(22) =       8.930698 [THz] =     297.898015 [cm-1]
omega(23) =       9.323473 [THz] =     310.999665 [cm-1]
omega(24) =       9.878343 [THz] =     329.508231 [cm-1]
omega(25) =      10.581080 [THz] =     352.949188 [cm-1]
omega(26) =      11.214091 [THz] =     374.064288 [cm-1]
omega(27) =      11.299609 [THz] =     376.916881 [cm-1]
omega(28) =      11.865318 [THz] =     395.787052 [cm-1]
omega(29) =      12.016973 [THz] =     400.845740 [cm-1]
omega(30) =      12.304312 [THz] =     410.430402 [cm-1]
omega(31) =      13.491423 [THz] =     450.028405 [cm-1]
omega(32) =      14.502625 [THz] =     483.758708 [cm-1]
omega(33) =      14.635485 [THz] =     488.190483 [cm-1]
omega(34) =      15.048602 [THz] =     501.970660 [cm-1]
omega(35) =      15.776018 [THz] =     526.234805 [cm-1]
omega(36) =      17.267246 [THz] =     575.977162 [cm-1]
omega(37) =      17.900635 [THz] =     597.104868 [cm-1]
omega(38) =      18.180537 [THz] =     606.441468 [cm-1]
omega(39) =      18.197251 [THz] =     606.998978 [cm-1]
omega(40) =      18.545524 [THz] =     618.616204 [cm-1]
omega(41) =      20.317191 [THz] =     677.713051 [cm-1]
omega(42) =      23.728955 [THz] =     791.517987 [cm-1]
omega(43) =      34.015744 [THz] =    1134.650635 [cm-1]
omega(44) =      35.280937 [THz] =    1176.853218 [cm-1]
omega(45) =      42.068145 [THz] =    1403.251608 [cm-1]
omega(46) =      46.532727 [THz] =    1552.175006 [cm-1]
omega(47) =      86.122480 [THz] =    2872.755808 [cm-1]
omega(48) =      89.220661 [THz] =    2976.100690 [cm-1]
**************************************************************************

Mode symmetry, C_1 (1)     point group:

omega(  1 -  1) =       -219.4  [cm-1]   --> A               I+R
omega(  2 -  2) =       -140.4  [cm-1]   --> A               I+R
omega(  3 -  3) =        -74.4  [cm-1]   --> A               I+R
omega(  4 -  4) =        -32.4  [cm-1]   --> A               I+R
omega(  5 -  5) =        -28.9  [cm-1]   --> A               I+R
omega(  6 -  6) =         65.8  [cm-1]   --> A               I+R
omega(  7 -  7) =         70.1  [cm-1]   --> A               I+R
omega(  8 -  8) =         84.3  [cm-1]   --> A               I+R
omega(  9 -  9) =        109.5  [cm-1]   --> A               I+R
omega( 10 - 10) =        123.6  [cm-1]   --> A               I+R
omega( 11 - 11) =        138.2  [cm-1]   --> A               I+R
omega( 12 - 12) =        150.2  [cm-1]   --> A               I+R
omega( 13 - 13) =        171.3  [cm-1]   --> A               I+R
omega( 14 - 14) =        187.9  [cm-1]   --> A               I+R
omega( 15 - 15) =        195.3  [cm-1]   --> A               I+R
omega( 16 - 16) =        210.3  [cm-1]   --> A               I+R
omega( 17 - 17) =        218.5  [cm-1]   --> A               I+R
omega( 18 - 18) =        240.9  [cm-1]   --> A               I+R
omega( 19 - 19) =        244.1  [cm-1]   --> A               I+R
omega( 20 - 20) =        255.4  [cm-1]   --> A               I+R
omega( 21 - 21) =        256.7  [cm-1]   --> A               I+R
omega( 22 - 22) =        297.9  [cm-1]   --> A               I+R
omega( 23 - 23) =        311.0  [cm-1]   --> A               I+R
omega( 24 - 24) =        329.5  [cm-1]   --> A               I+R
omega( 25 - 25) =        352.9  [cm-1]   --> A               I+R
omega( 26 - 26) =        374.1  [cm-1]   --> A               I+R
omega( 27 - 27) =        376.9  [cm-1]   --> A               I+R
omega( 28 - 28) =        395.8  [cm-1]   --> A               I+R
omega( 29 - 29) =        400.8  [cm-1]   --> A               I+R
omega( 30 - 30) =        410.4  [cm-1]   --> A               I+R
omega( 31 - 31) =        450.0  [cm-1]   --> A               I+R
omega( 32 - 32) =        483.8  [cm-1]   --> A               I+R
omega( 33 - 33) =        488.2  [cm-1]   --> A               I+R
omega( 34 - 34) =        502.0  [cm-1]   --> A               I+R
omega( 35 - 35) =        526.2  [cm-1]   --> A               I+R
omega( 36 - 36) =        576.0  [cm-1]   --> A               I+R
omega( 37 - 37) =        597.1  [cm-1]   --> A               I+R
omega( 38 - 38) =        606.4  [cm-1]   --> A               I+R
omega( 39 - 39) =        607.0  [cm-1]   --> A               I+R
omega( 40 - 40) =        618.6  [cm-1]   --> A               I+R
omega( 41 - 41) =        677.7  [cm-1]   --> A               I+R
omega( 42 - 42) =        791.5  [cm-1]   --> A               I+R
omega( 43 - 43) =       1134.7  [cm-1]   --> A               I+R
omega( 44 - 44) =       1176.9  [cm-1]   --> A               I+R
omega( 45 - 45) =       1403.3  [cm-1]   --> A               I+R
omega( 46 - 46) =       1552.2  [cm-1]   --> A               I+R
omega( 47 - 47) =       2872.8  [cm-1]   --> A               I+R
omega( 48 - 48) =       2976.1  [cm-1]   --> A               I+R

**************************************************************************

………………
the ecutwfc of neb calculation is 30.0 Ry, the tr2_ph of vibration calculation is 1.0d-14.

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