Fe bcc element probe — e_hull degeneracy test (definitional equality case)
.cifDegeneracy probe for the MP phase-diagram route: elemental input. For an element, formation energy and eabovehull are definitionally equal (both = Eorb(element) − EDFT(elemental reference)), so this tests whether the route's ehull != eformation intake gate would false-positive on honest elemental rows, and whether negative e_hull is possible when Orb v3 energy differs in sign from the DFT reference. Parsed Im-3m, 2 atoms, a=2.866 Å, min dist 2.482 Å.