First principles calculations of hyperfine magnetic field in RECd compounds (RE=Ce,Gd and Er) using FP-LAPW ELK code

Abstract

SCALISE MACIEL, Levy. First principles calculations of hyperfine magnetic field in RECd compounds (RE = Ce, Gd, and Er) using FP-LAPW ELK code. 2020. 149 p. Dissertação (Mestrado em Tecnologia Nuclear)-Instituto de Pesquisas Energéticas e Nucleares-IPEN-CNEN/SP. São Paulo. The use of nuclear techniques, mainly Time Differential Perturbed Angular Correlation Spectroscopy (PAC), for the study of materials provides information on the interactions between the energy levels of an atomic nucleus with the electrmagnetic fields surrounding this nucleus, and this type of phenomenon is called Hyperfine Interactions (HI). The information on these interactions is contained in various hyperfine quantities, among which the most important are the Electric Field Gradient (EFG) and the Magnetic Hyperfine Field (MHF). Given the gigantic scientific capacity of electronic structure calculations based on Density Functional Theory (DFT), they are a great tool for the investigation of HIs either as a purely theoretical study or as an addition to experimental measurements. This work implies calculating the hyperfine magnetic field in the RECd compounds (RE = Ce, Pr, Gd, Nd, Sm, Tb, Dy, Ho, Er, Eu, Tm and Yb) with first principles methods based on the density functional theory using the FP-LAPW ELK code and comparing the outcome to the experimental results, as well as to those obtained with the WIEN2k code. To achieve this goal, calculations were carried out for the RECd compounds. Firstly, the parameters needed to apply the calculation methodology were optimized, then the calculations were carried out by varying the polarization of spins for each compound in order to investigate their impact on MHF. After that, the MHF and the density of states (DOS) of all compounds in their various spin polarization configurations were calculated, so that a more thorough analysis of the results became possible. The work concludes with four appendices, the first is an explanation of the Born-Oppenheimer Approximation used to treat many-body systems, the second contains the proofs of the two main theorems of the DFT, the Hohenberg-Kohn Theorems, the third is a step-by-step tutorial on how to start a calculation with the ELK and the fourth comprises the optimization graphs which haven't got into the main text.

Exchange interactions and Curie temperatures of the tetrametal nitrides Cr4N, Mn4N, Fe4N, Co4N, and Ni4N

“…The calculations presented in this work were done in the framework of density functional theory (DFT). In a first step, the lattice constants a and magnetic configurations were determined with high-accuracy full-potential linearized augmented plane wave (FLAPW) calculations with the elk code [30]. Tight numerical parameters were chosen 1 to ensure that the results are precise.…”

Electron–phonon interaction and superconductivity in BaIr2P2

“…The electronic structure was calculated with the Elk code [12], a highly-accurate FP-APW+lo method. The experimentally determined crystal structure of Berry et al (space group I4/mmm, a = 3.9469(8) Å, c = 12.559(5) Å, Ba at (0, 0, 0), Ir at (0, 0, 0.25) and P at ( ) z 0, 0, P , where = z 0.3532 P ) was used (see figure 1) [9].…”

The structural, magnetic and electronic properties of the ground state of the hexagonal LuMnO3 multiferroic

“…All calculations have been performed by the all-electron FP-LAPW+lo method [21,22], based on spin DFT [19] and implemented in the Elk (version 4.3.6) computer code [25]. In this method, the electronic wave functions, charge density, and crystal potential are expanded in spherical harmonics inside the non-overlapping spheres centered at each nuclear position (atomic spheres), and in-plane waves in the rest of the space (interstitial region).…”