Quantum Monte Carlo calculates bulk properties and magnetic ordering in iron

Quantum Monte Carlo (QMC) models electronic systems with high accuracy but its computational demands limit wider use. Few QMC calculations exist for solid-state systems and none comparing the energetic ordering of different spin configurations (magnetic states). Density-functional calculations with generalized-gradient-approximation exchange-correlation give correct magnetic ordering and accurate lattice constants and bulk moduli for bcc iron. However, the predicted cohesive energy differs from experiment by 0.5-1.0 eV. QMC-calculated bulk elastic properties for pure iron in the bcc, hcp and fcc phases compare with properties in the ferromagnetic, antiferromagnetic and nonmagnetic spin configurations.