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: 1 to 500

Maximum ionic / cell-relax steps. After the first SCF, ABACUS stops without moving atoms if force and stress are already below threshold. If the cap is hit, the latest geometry is still returned with converged=false.

Range: to 50

Cell convergence: maximum stress-tensor component in kbar. Volume and shape stop updating once all components are below this.

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.

Range: to 1

Ionic convergence: maximum atomic force in eV/Å. ABACUS LCAO recommendation is 0.04.

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.

Range: to 1

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)

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.