Atomic-Orbital and Plane-Wave Approaches to Ferromagnetic Properties of NixFe1-x Nanowires

MRS Advances ◽  
2017 ◽  
Vol 2 (9) ◽  
pp. 507-512
Author(s):  
Ikram Ziti ◽  
M. R. Britel ◽  
Chumin Wang
Keyword(s):  
Plane Wave ◽  
Ab Initio ◽  
Density Functional ◽  
Atomic Orbital ◽  
Magnetic Moments ◽  
Geometry Optimization ◽  
Magnetic Sensors ◽  
Magnetic Nanowires ◽  
Electronic Density ◽  
Periodic Arrays

ABSTRACTThere are growing interests on magnetic nanowires, due to their potential applications in magnetic sensors and recording devices. In this work, we report a comparative ab-initio study based on the Density Functional Theory (DFT) of NixFe1-x nanowire periodic arrays by using atomic-orbital and plane-wave basis respectively through DMol3 and CASTEP codes. After performing the geometry optimization, we calculate the spin-polarized electronic density of states, average interatomic distance, and magnetic moments. For pure Ni nanowires (x = 1, the dependence of the magnetic moment obtained from CASTEP calculations on the cutoff energy, as well as that from DMol3 on the thermal smearing parameter is analyzed in detail. Both ab-initio calculations predict close magnetic moments for each x, being slightly larger those of DMol3 obtained with significantly less computing cost. Finally, these DFT results are compared with experimental data and a good agreement is observed.

A theoretical study of the 77Se NMR and vibrational spectroscopic properties of SenS8–n ring molecules

2002 ◽  
Vol 80 (11) ◽  
pp. 1435-1443 ◽  
Author(s):  
J Komulainen ◽  
R S Laitinen ◽  
R J Suontamo
Keyword(s):  
Ab Initio ◽  
Density Functional ◽  
Chemical Shifts ◽  
Atomic Orbital ◽  
Geometry Optimization ◽  
Spectroscopic Properties ◽  
Basis Sets ◽  
Orbital Method ◽  
Hybrid Functional ◽  
Ring Molecules

The structures and spectroscopic properties of SenS8–n ring molecules have been studied by the use of ab initio molecular orbital techniques and density functional techniques involving Stuttgart relativistic large core effective core potential approximation with double zeta basis sets for valence orbitals augmented by two polarization functions for both sulfur and selenium. Full geometry optimizations have been carried out for all 30 isomers at the Hartree-Fock level of theory. The optimized geometries and the calculated fundamental vibrations and Raman intensities of the SenS8–n molecules agree closely with experimental information where available. The nuclear magnetic shielding tensor calculations have been carried out by the Gauge-independent atomic orbital method at the DFT level using Becke's three-parameter hybrid functional with Perdew/Wang 91 correlation. The isotropic shielding tensors correlate well with the observed chemical shift data. The calculated chemical shifts provide a definite assignment of the observed 77Se NMR spectroscopic data and can be used in the prediction of the chemical shifts of unknown SenS8–n ring molecules.Key words: selenium sulfides, ab initio, DFT, effective core potentials, geometry optimization, energetics, fundamental vibrations, 77Se chemical shifts.

Boron Segregation on the ${\rm Si}(111)\sqrt{3} \times \sqrt{3}{\rm R}30^\circ$ Surface

2003 ◽  
Vol 10 (02n03) ◽  
pp. 201-205 ◽  
Author(s):  
Hongqing Shi ◽  
M. W. Radny ◽  
P. V. Smith
Keyword(s):  
Plane Wave ◽  
Ab Initio ◽  
Density Functional ◽  
Strong Support ◽  
Am1 Calculations ◽  
Segregation Energy ◽  
Additional Information ◽  
Boron Segregation ◽  
Cluster Calculations ◽  
Functional Code

In this paper we report the results of calculations of the energies associated with the segregation of boron on the [Formula: see text] surface. These calculations have been carried out using the plane wave pseudopotential density functional code fhi98md in a periodic slab formalism. The segregation energy is predicted to be -0.77 eV. This prediction is intermediate between the "experimentally determined" values of -0.33 eV and -0.48 eV, and the values of -1.83 eV and -2.10 eV determined from AM1 cluster calculations. Additional information has been obtained by performing ab initio density functional cluster calculations using the Gaussian98 code. These latter results indicate that the AM1 calculations significantly overestimate the segregation energy of boron on the [Formula: see text] surface. They also provide strong support for the fhi98md calculations.

scholarly journals Impact of Nano-Scale Distribution of Atoms on Electronic and Magnetic Properties of Phases in Fe-Al Nanocomposites: An Ab Initio Study

Nanomaterials ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 1059 ◽  
Author(s):  
Ivana Miháliková ◽  
Martin Friák ◽  
Yvonna Jirásková ◽  
David Holec ◽  
Nikola Koutná ◽  
...  
Keyword(s):  
Ab Initio ◽  
Density Functional ◽  
Nearest Neighbor ◽  
Magnetic Moments ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Α Phase ◽  
Ordered Intermetallic ◽  
Random Structures ◽  
The Impact

Quantum-mechanical calculations are applied to examine magnetic and electronic properties of phases appearing in binary Fe-Al-based nanocomposites. The calculations are carried out using the Vienna Ab-initio Simulation Package which implements density functional theory and generalized gradient approximation. The focus is on a disordered solid solution with 18.75 at. % Al in body-centered-cubic ferromagnetic iron, so-called α -phase, and an ordered intermetallic compound Fe 3 Al with the D0 3 structure. In order to reveal the impact of the actual atomic distribution in the disordered Fe-Al α -phase three different special quasi-random structures with or without the 1st and/or 2nd nearest-neighbor Al-Al pairs are used. According to our calculations, energy decreases when eliminating the 1st and 2nd nearest neighbor Al-Al pairs. On the other hand, the local magnetic moments of the Fe atoms decrease with Al concentration in the 1st coordination sphere and increase if the concentration of Al atoms increases in the 2nd one. Furthermore, when simulating Fe-Al/Fe 3 Al nanocomposites (superlattices), changes of local magnetic moments of the Fe atoms up to 0.5 μ B are predicted. These changes very sensitively depend on both the distribution of atoms and the crystallographic orientation of the interfaces.

Theoretical Study on Ni2XIn (X=Mn, Fe and Co) Magnetic Shape Memory Alloys by Ab Initio Calculations

2013 ◽  
Vol 712-715 ◽  
pp. 288-292 ◽  
Author(s):  
Jing Bai ◽  
Jiang Long Gu ◽  
Wen Qi Liu ◽  
Xin Wang ◽  
Yan Ming Wang ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Ab Initio ◽  
Density Functional ◽  
Magnetic Shape Memory ◽  
Magnetic Shape Memory Alloys ◽  
Austenitic Phase ◽  
Electronic Density ◽  
Functional Theory

The crystallographic, magnetic and electronic structures of the magnetic shape memory alloys Ni2XIn (X=Mn, Fe and Co) are systematically investigated by means of theab initiocalculations within the framework of density functional theory. The equilibrium lattice parameters and the bulk modulus of the austenitic phase in Ni2XIn are systematically calculated. The formation energy of the L21phase of the Ni2XIn is estimated, and displays a destabilization tendency if Mn atom is substituted by Fe or Co. Furthermore, the magnetic properties of the Ni2XIn have been investigated, and the essence of the variation in the magnetic properties with the X atomic number has been illustrated from the view of the electronic density of states.

Magnetic and Electronic Properties of LiVOPO4 and VOPO4 Cathodes

SPIN ◽  
2018 ◽  
Vol 08 (02) ◽  
pp. 1850003
Author(s):  
R. Masrour ◽  
A. Jabar ◽  
H. Moujri ◽  
E. K. Hlil ◽  
S. Obbade ◽  
...  
Keyword(s):  
Ab Initio Calculations ◽  
Ab Initio ◽  
Electronic Properties ◽  
Density Functional ◽  
Magnetic Moments ◽  
Mean Field Theory ◽  
Mean Field ◽  
Full Potential ◽  
Theory Approach ◽  
Flapw Method

Magnetic and electronic properties of LiVOPO4 and VOPO4 cathodes have been studied using ab initio calculations, high temperature series expansions (HTSEs) calculations and Monte Carlo simulations (MCSs). Self-consistent ab initio calculations, based on Density Functional Theory approach (DFT) and using Full Potential Linear Augmented Plane Wave (FLAPW) method, were performed to investigate both electronic and magnetic properties of the LiVOPO4. Polarized spin and spin–orbit coupling are included in calculations within the framework of the antiferromagnetic state between two adjacent V plans. Magnetic moments considered to lie along (010) axes are computed. Average equilibrium voltage over a full cycle ([Formula: see text]) of the LiVOPO4, battery have been estimated. Computed magnetic moments are used as input for HTSEs to compute other magnetic parameters using the mean field theory, MCSs and HTSEs. The obtained results by HTSEs and MCSs are comparable with experiments results.

Nanoroots of Quantum Chemistry

2014 ◽  
pp. 123-162
Author(s):  
Mihai V. Putz
Keyword(s):  
Quantum Chemistry ◽  
Density Functional ◽  
Chemical Space ◽  
Atomic Orbital ◽  
Life Time ◽  
Chemical Hardness ◽  
Electronic Density ◽  
Functional Theory ◽  
Gauge Transformations ◽  
Chemical Descriptors

This chapter identifies specific roots of chemistry and quantum chemistry and advances the idea that length and energy carry major roles at the nano-quantum level. A detailed exposition of this binom is unfolded under the specific radii-electronegativity or radii-chemical hardness that is then naturally extended to the radii-chemical descriptors relationships, having the atomic periodicity as the main benchmark check for their reliability. As such, considering different analytic electronegativity scales, they are reported and compared to the respective atomic orbital radii scales, both for the electronic density formulation, as uniform atomic electronic assembly, and for Slater type density orbital, respectively. The scheme for atomic orbital radii is further generalized by chemical descriptors in the frame of density functional theory. Finally, the chemical bond is treated through introducing the chemical quantum particle-the bondon-as a molecular nano-reality in modeling the energy-length space towards the chemical space, or bonding and reactivity. The existence of the chemical field along the associate bondon particle characterized by its mass , velocity , charge , and life-time are revealed by employing the combined Bohmian quantum formalism with the U(1) and SU(2) gauge transformations of the non-relativistic wave-function and the relativistic spinor, within the Schrödinger and Dirac quantum pictures of electronic motions.

Interfacial Spin Polarization and Magnetic Structure of Co/MgO/Co Magnetic Tunnel Junction: Ab Initio Calculation

2008 ◽  
Vol 8 (4) ◽  
pp. 2016-2021 ◽  
Author(s):  
Chiho Kim ◽  
Yong-Chae Chung
Keyword(s):  
Ab Initio ◽  
Spin Polarization ◽  
Tunnel Junction ◽  
Density Functional ◽  
Magnetic Moments ◽  
Magnetic Tunnel Junction ◽  
Equilibrium Structure ◽  
The Density Functional Theory ◽  
Spin Polarizability ◽  
Junction Structure

Using ab initio method based on the density functional theory, the equilibrium bcc-Co(001)/rocksalt-MgO(001)/bcc-Co(001) magnetic tunnel junction structure was investigated. Spin polarization and magnetic moment were calculated for each atomic slab in the equilibrium structure by spin dependent density of states analysis. Interfacial Co atoms showed significantly larger spin polarization of –88.3%, compared to the value of inner Co slabs, –82.3%, and bulk bcc Co, –82.1%. Interestingly, Mg and O atoms also showed induced spin polarizability ranged from –45.0% to –66.0%, except for O atoms in the centered slab of barrier layer, which showed relatively small polarization, –14.9%. Magnetic moments for the electrode Co atoms were calculated to be ∼1.74 μB with no significant variation across the electrode.

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