Many-body renormalization of forces in f-electron materials

TY - JOUR

T1 - Many-body renormalization of forces in f-electron materials

AU - Plekhanov, Evgeny

AU - Hasnip, Phil

AU - Sacksteder, Vincent

AU - Probert, Matt

AU - Clark, Stewart J.

AU - Refson, Keith

AU - Weber, Cedric

PY - 2018/8

Y1 - 2018/8

N2 - 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.

AB - 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.

UR - https://www.scopus.com/pages/publications/85051821394

U2 - 10.1103/PhysRevB.98.075129

DO - 10.1103/PhysRevB.98.075129

M3 - Article

AN - SCOPUS:85051821394

SN - 1098-0121

VL - 98

SP - 1

EP - 11

JO - Physical Review B (Condensed Matter and Materials Physics)

JF - Physical Review B (Condensed Matter and Materials Physics)

IS - 7

M1 - 075129

ER -