Checking for a True Minima

[Olivia Lynes]

Hi all,

I'm a new user of CP2K and have started off doing direct cell optimisations 
on  32/64/128 water boxes. The aim is to introduce small atoms into the 
water boxes and look at the behaviour.

All of the cell optimisations have completed, is there a way to check that 
the optimised geometry has reached a true minima not a maxima? 

Previously I would do a vibrational frequency analysis which gave the 
vibrational frequencies and infra-red spectra and if imaginary frequencies 
were found distort the geometry along the imaginary frequency and then 
re-optimise the structure. . 

Is there something similar I can do using CP2K?

Is it just a case of once the cell optimisation is complete altering the 
input file so RUN_TYPE is VIBRATIONAL_ANALYSIS and including a 
VIBRATIONAL_ANALYSIS section? I'm a bit unsure of what the input section 
for this type of job should look like, would I need to remove the CELL_OPT 
section?

If anyone has any suggestions of where I might begin with this that would 
be great. Apologies if the questions seem a bit simple I want to make sure 
I'm not misunderstanding things right at the beginning.

Many thanks

Olivia
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