The behavior of f-levels in hcp and bcc rare-earth elements in the ground state and XPS and BIS spectroscopy from density-functional theory

J Phys Condens Matter. 2014 Apr 16;26(15):155503. doi: 10.1088/0953-8984/26/15/155503. Epub 2014 Mar 27.

Abstract

The electronic structures of rare-earth elements in the hexagonal close-packed structure and Europium in the body-centered cubic structure are calculated using density-functional theory (DFT). X-ray photoemission spectroscopy (XPS) and bremsstrahlung isochromatic spectroscopy (BIS) simulations are made within DFT by implying that the f-electrons are excited by a large photon energy, either by removal from the occupied states in XPS or by addition to the unoccupied f-states in BIS. The results show sizable differences in the apparent position of the f-states compared to the f-band energy of the ground states. This result is fundamentally different from calculations assuming strong on-site correlation, since all the calculations are based on DFT. The spin-orbit coupling and multiplet splittings are not included, and the present simulation accounts for almost half of the difference between the f-level positions in the DFT ground states and the observed f-level positions. The electronic specific-heat at low T is compatible with the DFT ground state, where f-electrons often reside at the Fermi level.

MeSH terms

  • Computer Simulation
  • Crystallography, X-Ray
  • Electrons*
  • Europium / chemistry*
  • Metals, Rare Earth / chemistry*
  • Models, Molecular
  • Molecular Structure
  • Photoelectron Spectroscopy
  • Quantum Theory*
  • Spin Labels

Substances

  • Metals, Rare Earth
  • Spin Labels
  • Europium