Many-body renormalization of forces in f-electron materials

Plekhanov, Evgeny; Hasnip, Phil; Sacksteder, Vincent; Probert, Matt; Clark, Stewart J.; Refson, Keith; Weber, Cedric

Abstract

We present the implementation of dynamical mean-field theory (DMFT) in the CASTEP ab initio code. We explain in detail the theoretical framework for DFT+DMFT and we demonstrate our implementation for three strongly-correlated systems with f -shell electrons: γ -cerium, cerium sesquioxide Ce2O3, and samarium telluride SmTe by using a Hubbard I solver. We find very good agreement with previous benchmark DFT+DMFT calculations of cerium compounds, while for SmTe we show the improved agreement with the experimental structural parameters as compared with LDA. Our implementation works equally well for both norm-conserving and ultrasoft pseudopotentials, and we apply it to the calculation of total energy, bulk modulus, equilibrium volumes, and internal forces in the two cerium compounds. In Ce2O3 we report a dramatic reduction of the internal forces acting on coordinates not constrained by unit cell symmetries. This reduction is induced by the many-body effects, which can only be captured at the DMFT level. In addition, we derive an alternative form for treating the high-frequency tails of the Green function in Matsubara frequency summations. Our treatment allows a reduction in the bias when calculating the correlation energies and occupation matrices to high precision.

Citation

Plekhanov, E., Hasnip, P., Sacksteder, V., Probert, M., Clark, S. J., Refson, K., & Weber, C. (2018). Many-body renormalization of forces in f-electron materials. Physical review B, 98(7), Article 075129. https://doi.org/10.1103/physrevb.98.075129

• Journal Article Type: Article
• Acceptance Date: Jul 5, 2018
• Online Publication Date: Aug 16, 2018
• Publication Date: Aug 16, 2018
• Deposit Date: Aug 30, 2018
• Publicly Available Date: Aug 30, 2018
• Journal: Physical review B - Condensed Matter and Materials Physics
• Print ISSN: 1098-0121
• Electronic ISSN: 1550-235X
• Publisher: American Physical Society
• Peer Reviewed: Peer Reviewed
• Volume: 98
• Issue: 7
• Article Number: 075129
• DOI: https://doi.org/10.1103/physrevb.98.075129
• Public URL: https://durham-repository.worktribe.com/output/1350406
• Related Public URLs: https://arxiv.org/abs/1804.06805