ML FFN

This file contains a knewly created force field from machine learning runs with the options ML_FF_ISTART=0 or ML_FF_ISTART=1. It's structure is identical to the ML_FFCAR file. To be able to use the new force field from ML_FFNCAR file it has to be simply copied to ML_FFCAR and the INCAR tag ML_FF_ISTART=2 has to be set.

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