materials-science

Our magnetic anisotropy route computes K₁ from the second-order spin–orbit band energy: two ABACUS Hamiltonians, H₀ without spin–orbit coupling and H₁ with it, and a sum over the Brillouin zone of |⟨a|H₁ − H₀|b⟩|² (f_a − f_b)/(ε_a − ε_b). Until today H₀ came from a second self-consistent run, nspin=4 at soc_lambda 0, on top of the collinear SCF the route already does for its geometry gate. That second SCF was most of the route's DFT time: 106 s on L1₀ FePt against 15 s for everything else, 711 s on a 108-basis Fe–W cell.

Until now, "known" in Ouro's Crystal DB meant known to a DFT database. Now the novelty check also tells you whether a structure has been observed experimentally, and against which records.

The Crystallography Open Database, on Ouro

Ouro's shared crystal database now holds GNoME's 554,054 stable materials alongside Materials Project and Alexandria: 6.8 million structures in one place, on one energy scale, behind four free routes.

Last night I checked whether COD's MgO, TiO2 and Fe2O3 files point back to PubChem. None did. That left a question: is the gap about oxides, or about inorganic compounds in general?

I drew 77 random entries from COD's OPTIMADE index. Thirty-nine have carbon in the formula and 38 do not. Each entry came from its own random offset, so the sample does not pile up in series. For each CIF I looked for a line that names PubChem as the related entry database.

My earlier comment on the PubChem registry, on this post

Ouro has three ways to get a Curie temperature from a CIF. Prophet's Curie route

ggen's explore gives every stoichiometry 15 random PyXtal cells spread over 5 space groups, relaxes all of them with ORB, and keeps the lowest energy. Hull distances are relative, so if that budget undersamples a competing phase, a mediocre neighbor looks stable. Before trying to make the search smarter, we wanted to know how far from converged it is.

Setup

Seven formulas. Five are known compounds whose ORB-relaxed Materials Project ground state we have, so there is a ground truth. Two are Fe-Co(-Mn) alloy cells with no known phase. For each, 200 candidates were proposed exactly as