2. The Essentials of Density Functional Theory and the Full-Potential Local-Orbital Approach

2004 ◽  
pp. 7-21 ◽  
Author(s):  
H. Eschrig
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Full Potential ◽  
Functional Theory

Density Functional Theory Approach for Muon Sites Estimation in Mn3Sn

2021 ◽  
Vol 1028 ◽  
pp. 199-203
Author(s):  
Fiqhri Heda Murdaka ◽  
Edi Suprayoga ◽  
Abdul Muizz Pradipto ◽  
Kohji Nakamura ◽  
Agustinus Agung Nugroho
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Local Density ◽  
Full Potential ◽  
Theory Approach ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Electrostatic Potential Calculation ◽  
A Site ◽  
Linearized Augmented Plane Wave

We report the estimation of muon sites inside Mn3Sn using density functional theory based on the full-potential linearized augmented plane wave (FLAPW) calculation. Our calculation shows that the Perdew–Burke–Ernzerhof (PBE) Generalized-Gradient Approximation (GGA) functional is closer to the experimental structure compared to the von Barth-Hedin Local Density Approximation (LDA)-optimized geometry. The PBE GGA is therefore subsequently used in FLAPW post-calculation for the electrostatic potential calculation to find the local minima position as a guiding strategy for estimating the muon site. Our result reveals at least two muon sites of which one is placed at the center between two Mn-Sn triangular layers (A site) and the other at the trigonal prismatic site of Sn atom (B site). The total energy of Mn3Sn system in the presence of muon at A site or B site are compared and we find that A site is a more favorable site for muon to stop.

exciting: a full-potential all-electron package implementing density-functional theory and many-body perturbation theory

2014 ◽  
Vol 26 (36) ◽  
pp. 363202 ◽  
Author(s):  
Andris Gulans ◽  
Stefan Kontur ◽  
Christian Meisenbichler ◽  
Dmitrii Nabok ◽  
Pasquale Pavone ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Perturbation Theory ◽  
Density Functional ◽  
Full Potential ◽  
Many Body ◽  
Functional Theory ◽  
Many Body Perturbation Theory

scholarly journals Relativistic density functional theory in the full potential linear muffin tin orbital method

2020 ◽  
Author(s):  
Daniel Adam Rehn ◽  
Torbjorn Bjorkman ◽  
Ann Elisabet Wills ◽  
John Michael Wills
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Orbital Method ◽  
Full Potential ◽  
Functional Theory ◽  
Linear Muffin Tin Orbital

Post-perovskite CaIrO3: a conventional Slater type antiferromagnetic insulator

2016 ◽  
Vol 18 (37) ◽  
pp. 26300-26305 ◽  
Author(s):  
Vijeta Singh ◽  
J. J. Pulikkotil
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Coulomb Repulsion ◽  
Orbit Coupling ◽  
Full Potential ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Slater Type ◽  
Potential Density ◽  
Functional Theory

To resolve the controversy of whether or not the origin of an electronic gap in antiferromagnetic post-perovskite (pPv) CaIrO3 is due to Coulomb repulsion or spin–orbit coupling, and/or both, we have performed comprehensive full potential density functional theory based calculations.

scholarly journals RESEARCH OF THERMOMETRIC MATERIAL Er1-xScxNiSb. I. MODELLING OF PERFORMANCES

2021 ◽  
Vol 82 (2) ◽  
pp. 16-21
Author(s):  
Volodymyr Krayovskyy ◽  
◽  
Volodymyr Pashkevych ◽  
Andriy Horpenuk ◽  
Volodymyr Romaka ◽  
...  
Keyword(s):  
Solid Solution ◽  
Density Functional Theory ◽  
Fermi Level ◽  
Valence Band ◽  
Density Functional ◽  
Continuous Solid Solution ◽  
Unit Cell ◽  
Full Potential ◽  
Functional Theory ◽  
Thermometric Material

Automated The results of modeling performances of the semiconductor solid solution Er1-xScxNiSb are presented, which can be a promising thermometric material for the manufacture of sensitive elements of thermoelectric and electroresistive thermocouples. Fullprof Suite software was used to model the crystallographic characteristics of the Er1-xScxNiSb thermometric material. Modeling of the electronic structure of Er1-xScxNiSb was performed by Coring-Kon-Rostocker methods in the approximation of coherent potential and local density using the exchange-correlation potential Moruzzi-Janak-Williams and Linear Muffin-Tin Orbital in the framework of DFT density functional theory. The Brillouin zone was divided into 1000 k-points, which were used to model energetic performances by calculating DOS. The width of the energy window was 22 eV and was chosen to capture all semi-core states of p-elements. Full potential (FP) was used in the representation of the linear MT orbital in the representation of plane waves. The accuracy of calculating the position of the Fermi level was εF ± 6 meV. To verify the existence of a continuous solid solution, Er1-xScxNiSb substitution, the change in the values of the period of the unit cell a (x) was calculated within the framework of the DFT density functional theory in the range x = 0–1.0. It is presented that the calculated and experimentally obtained dependences of the period of the unit cell a(x) Er1-xScxNiSb are almost parallel, which confirms the correctness of the used tools and the obtained modeling results. To research the possibility of obtaining thermometric material Er1-xScxNiSb in the form of a continuous solid solution was performed modeling of thermodynamic calculations in the approximation of harmonic oscillations of atoms in the theory of DFT density functional for a hypothetical solid solution Er1-xScxNiSb, x = 0–1.0. It is shown that the change in the values of free energy ΔG(x) (Helmholtz potential) passes through the minimum at the concentration x≈0.1 for all temperatures of possible homogenizing annealing of the samples, indicating the solubility limit of Sc atoms in the structure of the ErNiSb compound. The presence of this minimum indicates that the substitution of Er atoms for Sc atoms in the ErNiSb compound is energetically advantageous only up to the concentration of impurity atoms Sc, x≈0.1. At higher concentrations of Sc atoms, x> 0.10, stratification occurs (spinoidal phase decay). It is shown that modeling of the mixing entropy behavior S even at a hypothetical temperature T = 4000 K shows the absence of complete solubility of Sc atoms in Er1-xScxNiSb. To model the energetic and kinetic performances of the semiconductor thermometric material Er1-xScxNiSb, particularly the behavior of the Fermi level F e , bandgap width g e the distribution of the density of electronic states (DOS) and the behavior of its electrical resistance ρ(x, T) is calculated for an ordered variant of the structure in which the Er atoms in position 4a are replaced by Sc atoms. It is shown that the ErNiSb compound is a semiconductor of the electronic conductivity type, in which the Fermi level is located near the level of the conduction band C e . The modeling showed that at higher concentrations of Sc atoms, the number of generated acceptors exceeds the concentration of uncontrolled donors, and the concentration of free holes exceeds the concentration of electrons. Under these conditions, the Fermi level F e approaches, and then the level of the valence band Er1- xScxNiSb crosses: the dielectric-metal conductivity transition occurs. The experiment should change the sign of the thermo-emf coefficient α(x, T) Er1-xScxNiSb from negative to positive, and the intersection of the Fermi level F e and the valence band changes the conductivity from activating to metallic: on the dependences ln(ρ(1/T)) the activation sites disappear, and the values of resistivity ρ increase with temperature.

scholarly journals Covariant Density Functional Theory in Nuclear Physics and Astrophysics

2020 ◽  
Vol 70 (1) ◽  
pp. 21-41 ◽  
Author(s):  
Junjie Yang ◽  
J. Piekarewicz
Keyword(s):  
Density Functional Theory ◽  
Neutron Stars ◽  
Nuclear Physics ◽  
Density Functional ◽  
Theoretical Research ◽  
Electromagnetic Spectrum ◽  
Full Potential ◽  
Rare Isotope ◽  
Functional Theory ◽  
Nuclear Density Functional Theory

How does subatomic matter organize itself? Neutron stars are cosmic laboratories uniquely poised to answer this fundamental question that lies at the heart of nuclear science. Newly commissioned rare isotope facilities, telescopes operating across the entire electromagnetic spectrum, and ever more sensitive gravitational wave detectors will probe the properties of neutron-rich matter with unprecedented precision over an enormous range of densities. A coordinated effort between observation, experiment, and theoretical research is of paramount importance for realizing the full potential of these investments. Theoretical nuclear physics provides valuable insights into the properties of neutron-rich matter in regimes that are not presently accessible to experiment or observation. In particular, nuclear density functional theory is likely the only tractable framework that can bridge the entire nuclear landscape by connecting finite nuclei to neutron stars. This compelling connection is the main scope of the present review.

scholarly journals Electronic properties of palladium diselenide by density functional theory

2017 ◽  
Vol 13 (3) ◽  
Author(s):  
Ying Xuan Ng ◽  
Rashid Ahmed ◽  
Abdullahi Lawal ◽  
Bakhtiar Ul Haq ◽  
Afiq Radzwan ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Band Gap ◽  
Electronic Properties ◽  
Density Functional ◽  
Band Gap Energy ◽  
Partial Density ◽  
Full Potential ◽  
Functional Theory ◽  
Lattice Constants ◽  
Gap Energy

The knowledge of the structural and electronic properties of a material is important in various applications such as optoelectronics and thermoelectric devices. In this study, we are using full potential linearized augmented plane wave method framed within density functional theory provided by WIEN2k to optimize the structure of PdSe2 in orthorhombic (Pbca) phase and calculate its electronic properties. With the implementation of local density approximation (LDA), Perdew-Burke-Ernzerhof parameterization of generalized gradient approximation (PBE-GGA), Wu-Cohen parameterization of GGA (WC-GGA), and PBE correction for solid GGA (PBEsol-GGA), the computed results of lattice constants are found to be within 5% error with the experiment data. Also, our calculated indirect band gap energy was found to be ~0.24 eV by LDA along with modified Becke-Johnson potential functional (mBJ) with experimental lattice constants and ~0.52 eV by using PBE-GGA with optimized lattice constants. However, the effect of spin-orbit coupling is not found too much on the band gap energy. By analyzing the partial density of states, we identify that d-orbital of Pd is demonstrating a slightly more significant contribution to both the valence and conduction band near to Fermi level which is also in agreement with the previous first principles study.

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