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Errors when including the tags of ML_FF for runs

Posted: Mon Jul 07, 2025 1:02 pm
by manoj_wijesingha

Hi Colleagues,
I tried to run freq1 and freq2 of these examples in the tutorial for IDM calculations (https://www.vasp.at/tutorials/latest/tr ... tes/part1/). When including the ML_FF tags, it gives an error message "ML_FF is missing". Without the tags of ML_FF, it runs nicely. So, I have installed VASP.6.5.1 successfully including the machine learning parts. I have attached files for you.

Best Regards,
Manoj.


Re: Errors when including the tags of ML_FF for runs

Posted: Mon Jul 07, 2025 2:15 pm
by alexey.tal

Dear Manoj,

Thank you for your question.

In this tutorial you should download a pre-trained machine-learned force field. The link to download the force field is shown in the very begging of the tutorial. Did you copy this file into your working directory?

Best wishes,
Alexey


Re: Errors when including the tags of ML_FF for runs

Posted: Mon Jul 07, 2025 4:21 pm
by manoj_wijesingha

Hi Alexey,
Yeah, I have copied the files to my working directly, and without ML_FF keywords, it worked. But I need to use the ML_FF for the simulations. So, how can I run the frequency with these MLFF tags.
Thank you.

Best regards,
Manoj.


Re: Errors when including the tags of ML_FF for runs

Posted: Tue Jul 08, 2025 8:24 am
by alexey.tal

In order to be able to run this exercies you need to have a copy of the ML force field in the working directory, i.e., e02_IDM/freq1.

The force field can be found here. For e02_IDM we need the file MLFF_e02/ML_FFN.bz2. This ML_FFN.bz2 file should be decompressed (bzip2 -d ML_FFN.bz2) and then the file ML_FFN should be renamed to ML_FF and copied to your working directory e02_IDM/freq1.

I hope that helps.


Re: Errors when including the tags of ML_FF for runs

Posted: Tue Jul 08, 2025 1:05 pm
by manoj_wijesingha

Great. Thank you and appreciate for this information. If we run the different systems for IDM and frequency calculations (I need to use MLFF tags), first we train these systems to obtain the ML_FNN file for next simulations, is this right? Could you please share the examples, tutorials or codes for the training.
Thanks.

Best Regards,
Manoj.


Re: Errors when including the tags of ML_FF for runs

Posted: Tue Jul 08, 2025 1:24 pm
by alexey.tal

Correct. If you want to perform IDA with MLFF on a different system you would first need to generate a force field for your system. Here you can find a tutorial for generating force fields.


Re: Errors when including the tags of ML_FF for runs

Posted: Wed Jul 09, 2025 11:43 am
by manoj_wijesingha

Thanks Alexey. I will ask this to my knowledge; so, after running the relaxed optimization of a system then we can perform ML_FF to generate force field (ML_FFN) which can be used for the next simulations like vibrational frequency. In IDM calculations, we train the data again for the coordinates of IDM to obtain the ML_FFN first and then perform the IDM. Is this right way and could you please explain this.
Thank you.

Best Regards,
Manoj.