Range: 20 to 500

Number of energy-contour points for TB2J integration

Lower bound of energy contour relative to Fermi level (eV)

Neighbor cutoff for Jij in Å (TB2J default if omitted)

Monkhorst-Pack mesh for TB2J. Defaults to twice the SCF mesh (kspacing/2); coarser meshes alias J(R) into non-decaying tails.

Collinear spin treatment. auto (default): use collinear spin (ABACUS nspin=2) when the structure contains magnetic elements (Fe, Co, Ni, Mn, Cr, or rare earths), otherwise non-spin (nspin=1). non_spin: force closed-shell (nspin=1). collinear: force spin-polarized DFT with seeded moments (nspin=2). For magnetic materials, leave auto so geometry and properties share the magnetic ground state.

Range: 30 to 150

Plane wave cutoff energy in Ry. The default matches the 100 Ry the orbitals are generated for; at 50 Ry L1_0 FePt MAE comes out 50% high.

SCF convergence threshold on the charge-density residual (ABACUS scf_thr; not an energy). The default suits screening; ABACUS's own LCAO default is 1e-7. Tighten to 1e-6 or below when comparing small energy differences such as ordering margins.

Range: 0.05 to 1

K-point spacing in 1/Å

Range: 20 to 500

Maximum number of SCF iterations

Turn on DFT+U with an effective U in eV per element, e.g. {"Ni": 6.2}. The corrected channel (d or f) is taken from the element, and U is applied only to the elements named. Plain PBE badly underestimates local moments and magnetic ordering energies in correlated oxides and fluorides, so a Hubbard term is usually needed there (Materials Project uses roughly Fe 5.3, Co 3.32, Ni 6.2, Mn 3.9, Cr 3.7, V 3.25, Cu 4.0). Setting this also softens the SCF defaults to mixing_beta 0.2 and scf_nmax 300, which correlated oxides need; an explicit value for either still wins. Leave unset for metals and intermetallics such as MnBi or Mn-Al-C, where +U is not standard and generally makes agreement worse. The scheme is Dudarev, so this is U minus Hund J, not bare U.

LCAO basis size: SZ (fastest), DZP (balanced), TZDP (most accurate)

Range: to 1

Charge mixing step (0–1). Default 0.4. Difficult magnets (Mn) often need 0.20, then 0.10 if SCF still oscillates.

Charge-density mixer: broyden (default, with Kerker for magnets), pulay, or plain linear mixing. Reduce mixing_beta before switching mixers.

XC functional

Signed starting moments in µB, one per atom in CIF site order. Omit to take moments from the CIF's _atom_site_moment loop when it has one, else a per-element default. Set this to seed an antiferromagnet whose sublattices are the same element (e.g. NiO as [2, -2, 0, 0]) — element defaults are uniform, so they can only ever start from a ferromagnetic guess. Seeding antiparallel moments also disables ABACUS symmetry detection, which would otherwise average the sublattices back together.

Magnetic-density mixing step. Omit for auto: 0.1 when spin-polarized, 1.0 otherwise. Lower (0.05–0.1) if moments oscillate.

Occupation and smearing method: fixed (non-conductors only), gauss/gaussian, mp (metals), mp2 (metals), mv/cold, fd (Fermi-Dirac)

Elements treated as magnetic sites for TB2J (e.g. Fe, Co, Ni). Defaults to magnetic species present in the structure.

Range: to 1

Occupation smearing width in eV (converted to Rydberg for ABACUS). Typical metals: 0.05–0.10 eV. Gaps need ~0.05 eV or smaller.

Evaluate the primitive cell instead of the cell as uploaded. Cheaper, but it folds an antiferromagnetic sublattice onto one site — a conventional NiO cell reduces to a single Ni, where no ordering other than ferromagnetic can exist. Leave false for any magnetic ordering question.