[CP2K-user] Calculating normal modes for a saddle point structure from NEB

[Mohammad Momeni Taheri]

Thanks Nico. I tried -5000 but still all of my frequencies are real! I 
tried the ethane example 
(https://www.cp2k.org/exercises:2016_uzh_cmest:path_optimization_neb) and 
did full and partial frequency calculations separately. For the full 
frequency case, I obtained three imaginary frequencies (304.8i cm-1, 142.5i 
cm-1, and 103.4i cm-1) however when I froze H3 and H4 and did 
mode_selective calculations all calculated frequencies became real. The 
relevant parts of my input and output files for the partial frequency run 
of ethane are pasted below. I can post my input and output for the full 
frequency case as well if needed.

Many thanks,
Mohammad

*Input*: 
.
.
.
&MOTION
  &CONSTRAINT
    &FIXED_ATOMS
      COMPONENTS_TO_FIX XYZ
      LIST 3..4
    &END FIXED_ATOMS
  &END CONSTRAINT
&END MOTION
.
.
.
&VIBRATIONAL_ANALYSIS
  NPROC_REP 16
  &MODE_SELECTIVE
    ATOMS 1 2 5 6 7 8 
    FREQUENCY -5000
    RANGE -5000 10
    &INVOLVED_ATOMS 
    INVOLVED_ATOMS 1 2 5 6 7 8
      RANGE -5000 10
    &END INVOLVED_ATOMS
  &END MODE_SELECTIVE
.
.
.

*Output*:

 REPLICA| layout of the replica grid, number of groups                     
    1
 REPLICA| layout of the replica grid, size of each group                   
   16
 REPLICA| MPI process to grid (group,rank) correspondence:
  (   0 :    0,   0)  (   1 :    0,   1)  (   2 :    0,   2)  (   3 :    0, 
  3)
  (   4 :    0,   4)  (   5 :    0,   5)  (   6 :    0,   6)  (   7 :    0, 
  7)
  (   8 :    0,   8)  (   9 :    0,   9)  (  10 :    0,  10)  (  11 :    0, 
 11)
  (  12 :    0,  12)  (  13 :    0,  13)  (  14 :    0,  14)  (  15 :    0, 
 15)
 MS| ITERATION STEP        1
 MS| TRACKED MODE     1252.008036cm-1  NOT  CONVERGED
 MS| ITERATION STEP        2
 MS| TRACKED MODE      769.913197cm-1  NOT  CONVERGED
 MS| ITERATION STEP        3
 MS| TRACKED MODE      439.855194cm-1  NOT  CONVERGED
 MS| ITERATION STEP        4
 MS| TRACKED MODE      405.817333cm-1  NOT  CONVERGED
 MS| ITERATION STEP        5
 MS| TRACKED MODE      331.609693cm-1  NOT  CONVERGED
 MS| ITERATION STEP        6
 MS| TRACKED MODE      307.669620cm-1  NOT  CONVERGED
 MS| ITERATION STEP        7
 MS| TRACKED MODE      299.612607cm-1  NOT  CONVERGED
 MS| ITERATION STEP        8
 MS| TRACKED MODE      269.847744cm-1  NOT  CONVERGED
 MS| ITERATION STEP        9
 MS| TRACKED MODE      223.476957cm-1  NOT  CONVERGED
 MS| ITERATION STEP       10
 MS| TRACKED MODE      164.744189cm-1  NOT  CONVERGED
 MS| DAVIDSON ALGORITHM CONVERGED
 MS| TRACKED FREQUENCY (1) IS:  113.384782   cm-1

 -------------------------------------------------------------------------------
                         FREQUENCY AND CONVERGENCE LIST
       FREQUENCY    MAXVAL CRITERIA    NORM CRITERIA    CONVERGENCE
  VIB|   113.385     0.154191E-06        0.347E-06           YES
  VIB|   352.500     0.138434E-06        0.311E-06           YES
  VIB|   693.978     0.260601E-06        0.586E-06           YES
  VIB|  1032.631     0.252407E-06        0.568E-06           YES
  VIB|  1265.788     0.132026E-05        0.300E-05           NO
  VIB|  1374.797     0.418727E-06        0.942E-06           YES
  VIB|  1463.690     0.148252E-06        0.337E-06           YES
  VIB|  2992.320     0.695927E-08        0.156E-07           YES
  VIB|  3040.591     0.168953E-06        0.384E-06           YES
  VIB|  3062.286     0.103910E-06        0.234E-06           YES
  VIB|  3067.058     0.373819E-06        0.841E-06           YES

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On Wednesday, 31 October 2018 00:23:17 UTC-7, Nico Holmberg wrote:
>
> Hi,
>
> The range keyword should indeed fix the issue. Try setting the lower value 
> to something smaller e.g. -5000.
>
> -Nico
>
>
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