Visualization of negative frequencies

[RASHMI BRAHMA]

Hello everyone

Can anyone tell me where can I visualize negative frequencies that is occurring in my system?

[RASHMI BRAHMA]

Hello

I am new to cp2k, and I keep getting negative frequencies even after optimization of the coordinates of my system. Can anyone help me how can i visualize those or remove those negative frequencies from my system? Please help me out.

[Victor Volkov]

Hello, dear Rashmi.

I am not a developer of CP2K.

First, may be, you need to search through previous communications on the discussion group

(using keywords like "vibrations", "normal modes" etc) to study them sorting what might be relevant or not.

Second, I do not think anybody would be able to give you a clear answer for your question

since setting a system and configuring various parameters is rather demanding - you would need to

attach an input that somebody would try to approach.

Third, the term you use "visualize" is not clear.

If you ask how to image atomic displacements about computed normal modes,

this concerns using other software but not CP2K.

For example, it is possible to use molden.

(Sometimes, I program displacement images in Mathematica.)

Again, using "visualize" is not clear.

I hope, these comments would help you to attract attention of the developers.

Victor

 

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[RASHMI BRAHMA]

I have attached the input file and outfput files generated from it. 

[Victor Volkov]

Hello Rashmi.

In the &GEO_OPT section, you have

    MAX_DR    1.0E-03
    MAX_FORCE 1.0E-03
    RMS_DR    1.0E-03
    RMS_FORCE 1.0E-03

May be, you need
    MAX_DR    1.0E-06
    RMS_DR    1.0E-06    
    MAX_FORCE 1.0E-07
    RMS_FORCE 1.0E-07

or even more demanding criteria.

Victor

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[RASHMI BRAHMA]

Hello Victor

Thank you for your suggestion. I have tried incorporating it in my input file, but I am still getting negative frequencies.

[Victor Volkov]

Good day, Rashmi.

Does VIBRATIONAL_ANALYSIS

employ the &GEO_OPT section (even if it is included in the input)

to run the structural optimization under the proper thresholds?

I am not sure.

I do not think so.

I run GEO_OPT as a devoted job prior

any vibrational analysis.

If you confirm optimization done according to the thresholds,

then, observing negative frequencies (upon the consequent vibrational analysis)

would be a proper question to post to the developers.

Sincerely,

Victor

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[RASHMI BRAHMA]

I have done optimization prior to frequency calculation. I have then put the optimized coordinates in the frequency input. 

[Victor Volkov]

Dear Rashmi,

you are at "the mercy" of the devs.

Victor

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