cutoff
This keyword enables one to specify the radial (\(r_\mathrm{c}^\mathrm{R}\)) and angular (\(r_\mathrm{c}^\mathrm{A}\)) cutoffs of the NEP model. One syntax is:
cutoff <radial_cutoff> <angular_cutoff>
where <radial_cutoff> and <angular_cutoff> correspond to \(r_\mathrm{c}^\mathrm{R}\) and \(r_\mathrm{c}^\mathrm{A}\), respectively.
The cutoffs must satisfy the conditions 2.5 Å \(\leq r_\mathrm{c}^\mathrm{A} \leq r_\mathrm{c}^\mathrm{R} \leq\) 10 Å.
The defaults are \(r_\mathrm{c}^\mathrm{R}\) = 8 Å and \(r_\mathrm{c}^\mathrm{A}\) = 4 Å. It can be computationally beneficial to use (possibly much) smaller \(r_\mathrm{c}^\mathrm{R}\) but the default values should be reasonable in most cases.
Another syntax is:
cutoff <radial_cutoff_species_1> <angular_cutoff_species_1> <radial_cutoff_species_2> <angular_cutoff_species_2> ...
which can be used to specify a set of radial and angular cutoffs for each species. The cutoff between two species (\(a\) and \(b\)) is the arithmetic average of the cutoffs for the two species: