spin_cutoff

This keyword sets the Spin3 cutoff distance in Å:

spin_cutoff <cutoff>
spin_cutoff <cutoff_type_1> ... <cutoff_type_N>

Use either one positive value, which is broadcast to all atom types, or exactly one positive value for every type in the order declared by type. If this keyword is absent, the largest ordinary radial cutoff is broadcast.

Every value must be less than or equal to the largest ordinary radial cutoff (rc_radial_max). The same restriction applies when reading a model file. To use a larger magnetic cutoff, increase the ordinary radial cutoff as well.

For an edge between types \(a\) and \(b\), Spin3 uses the arithmetic mean \((r_a^\mathrm{spin}+r_b^\mathrm{spin})/2\).

For example, with type 2 Fe Ge:

cutoff 6.0 5.0
spin_cutoff 4.0 6.0

uses 4, 5, and 6 Å for Fe–Fe, Fe–Ge, and Ge–Ge magnetic edges. The spin_cutoff line does not change the ordinary structural NEP cutoffs.