A Hybrid DFT Description of the Ground State Properties of Americium-I

Raymond Atta-Fynn; Asok K. Ray

A Hybrid DFT Description of the Ground State Properties of Americium-I

POSTER

Abstract

Americium-I (Am-I) is a strongly correlated metal which has been determined experimentally to be a non-magnetic, double HCP crystal with well-localized 5$f$ electrons. However, theoretical descriptions of Am-I based on density functional theory (DFT) yield the correct structural properties but the wrong magnetic ground state and a very poorly described 5$f$ electron spectra. In this work, we will show that hybrid DFT, which replaces a fraction (40{\%} to be exact) of approximate DFT exchange with exact Hartree-Fock (HF) exchange, yields structural, magnetic, and electronic properties of Am-I which are in excellent agreement with experimental data. The primary reason why DFT fails to describe Am-I, namely the overestimation of the exchange interaction leading to a spin-polarized ground state, and how this failure is corrected by hybrid DFT, will be discussed.

^*R. Atta-Fynn and A. K. Ray, Chemical Physics Letters, \textbf{482}, 223-227 (2009). This work is supported by the U. S. Department of Energy and the Welch Foundation, Houston, Texas.

Authors

Raymond Atta-Fynn
- Physics Department, The University of Texas at Arlington
- Physics Department, University of Texas at Arlington, Texas 76019
Asok K. Ray
- Physics Department, The University of Texas at Arlington
- Physics Department, University of Texas at Arlington, Texas 76019
- Physics Department, University of Texas at Arlington, TX 76019
- Department of Physics, University of Texas Arlington