Requests for technical support from the VASP group should be posted in the VASP-forum.
ML EATOM REF
ML_EATOM_REF = [real array]
Default: ML_EATOM_REF = 0.0
Description: Reference total energies of isolated atoms used in the machine learning force field method.
This tag is only used if ML_ISCALE_TOTEN=1.
By default this tag is not used since all energies are scaled to the average of the training data (ML_ISCALE_TOTEN=2).
If this tag is used, each reference energy should be obtained from a VASP calculation of an isolated atoms in a sufficiently large simulation box. The reference is then simply taken from the Helmholtz free energy from the OSZICAR file (value following "1 F=" in that file).
The reference energies are simply set in one line as a list for each species, i.e. like the following
ML_EATOM_REF = E_1 E_2 E_3 ...
where E_1, E_2, E_2 etc. are the energies for species 1, 2, 3 etc. (corresponding to the order they occur in the POTCAR file).
The unit of the energies is eV/atom.