First-Principles Analysis of impact of Hubbard U on Structural and Electronic Properties of Heusler Alloys

The role of Coulomb correlations in stoichiometric Ni 2 MnSn and off-stoichiometric Ni 2 Mn 1.5 Sn 0.5 Heusler alloys is examined using ab-initio calculations with GGA and GGA+U functionals. For Ni 2 MnSn, GGA accurately reproduces experimental lattice parameters, magnetic moments, and valence band spectra, while the inclusion of U on Mn or Ni leads to overestimated magnetic moments and spectral mismatches. In Ni 2 Mn 1.5 Sn 0.5 , GGA correctly predicts the martensitic tetragonal distortion and matches photoelectron spectroscopy measurements, whereas GGA+U suppresses this structural transition and fails to capture key electronic features. Overall, the study shows that the GGA exchange correlation functionals are sufficient to describe the structural, electronic and magnetic properties of Ni–Mn–Sn Heusler alloys, and additional U corrections may not be necessary.