First-Principles Momentum Dependent Local Ansatz Approach to the Ground-State Properties of Iron-Group Transition Metals

TL;DR

This paper uses a first-principles momentum dependent local ansatz theory to investigate the ground-state properties of iron-group transition metals, revealing significant correlation energies, charge fluctuations, and local magnetic moments consistent with experimental data.

Contribution

It introduces a first-principles MLA approach to accurately describe correlation effects and magnetic properties of transition metals, resolving previous theoretical inconsistencies.

Findings

Large correlation energy gains for Mn and Fe

Charge fluctuations are nearly constant across V to Fe

Local moments are enhanced and match experimental estimates

Abstract

The ground-state properties of iron-group transition metals from Sc to Cu have been investigated on the basis of the first-principles momentum dependent local ansatz (MLA) theory. Correlation energy gain is found to show large values for Mn and Fe: 0.090 Ry (Mn) and 0.094 Ry (Fe). The Hund-rule coupling energies are found to be 3000 K (Fe), 1400 K (Co), and 300 K (Ni). It is sugested that these values can resolve the inconsistency in magnetic energy between the density functional theory and the first-principles dynamical coherent potential approximation theory at finite temperatures. Charge fluctuations are shown to be suppressed by the intra-orbital correlations and inter-orbital charge-charge correlations, so that they show nearly constant values from V to Fe: 1.57 (V and Cr), 1.52 (Mn), and 1.44 (Fe), which are roughly twice as large as those obtained by the $d$ band model. The amplitudes of local moments are enhanced by the intra-orbital and inter-orbital spin-spin correlations and show large values for Mn and Fe: 2.87 (Mn) and 2.58 (Fe). These values are in good agreement with the experimental values estimated from the effective Bohr magneton number and the inner core photoemission data.