LML fit in bcc Fe with BSO4 descriptor, 2-body ZBL core

This section provides an example input file for performing a linear ML (LML) fit with a BSO4 descriptor for bcc Fe, combined with a short-range 2-body (K2B) correction and a ZBL repulsive core for close interatomic distances. The relevant files are provided in examples/lml_fe_bso4_zbl.

The ZBL potential takes over the many-body ML description below r1_zbl, with a smooth transition handled by K2B between r1_zbl and the inner many-body cutoff r_cut_in.

&input_ml
debug=.false.

!ML mode
ml_type=0                  !set 0 to perform the fit using basis functions
mld_order=1                !set 1 for linear regression

write_desc=.false.
desc_forces=.true.         !set true to fit the forces

!Define your system
weighted=.false.           !set true for multicomponent systems
chemical_elements=" Fe "   !provide the system composition

!Descriptor settings
r_cut=4.7d0                !set the cutoff distace Rc
descriptor_type=9          !set 9 for bispectrum SO4
j_max=4                    !angular moment for bispectrum SO4

!2-body (K2B) settings
activate_k2b=.true.
sigma_2b=0.3d0              !controls the smoothness of the interaction
delta_2b=1.d0                !controls the magnitude (in eV) of a typical 2-body interaction
np_radial_2b=40              !number of radial points in the 2-body grid
r_cut_in=1.5d0                !many-body interaction is shut down below this distance (Ang)
r_cut_width_in=0.3d0           !controls the smoothness of the inner cutoff
type_fcut=3                     !type of cutoff function

!ZBL settings
zbl_potential=.true.        !activate the ZBL repulsive core
r1_zbl=1.0d0                 !below this distance, only ZBL is used
r2_zbl=2.2d0                  !controls the smoothness of ZBL

&end