Ground state of the He2+2 molecular ion computed with density functional techniques

1982 ◽  
Vol 77 (12) ◽  
pp. 6348-6350 ◽  
Author(s):  
Miguel Castro ◽  
Jaime Keller ◽  
Oscar N. Ventura
Keyword(s):  
Ground State ◽  
Density Functional ◽  
Molecular Ion

Magnetic Ground State and Electronic Structure Calculations of PbMnO3 Using DFT

2014 ◽  
Vol 895 ◽  
pp. 420-423 ◽  
Author(s):  
Sathya Sheela Subramanian ◽  
Baskaran Natesan
Keyword(s):  
Electronic Structure ◽  
Band Structure ◽  
Fermi Level ◽  
Ground State ◽  
Density Functional ◽  
Electronic Structure Calculations ◽  
Magnetic Ground State ◽  
Electronic Band ◽  
Structure Calculations ◽  
Centrosymmetric Structure

Structural optimization, magnetic ground state and electronic structure calculations of tetragonal PbMnO3have been carried out using local density approximation (LDA) implementations of density functional theory (DFT). Structural optimizations were done on tetragonal P4mm (non-centrosymmetric) and P4/mmm (centrosymmetric) structures using experimental lattice parameters and our results indicate that P4mm is more stable than P4/mmm. In order to determine the stable magnetic ground state of PbMnO3, total energies for different magnetic configurations such as nonmagnetic (NM), ferromagnetic (FM) and antiferromagnetic (AFM) were computed for both P4mm and P4/mmm structures. The total energy results reveal that the FM non-centrosymmetric structure is found to be the most stable magnetic ground state. The electronic band structure, density of states (DOS) and the electron localization function (ELF) were calculated for the stable FM structure. ELF revealed the distorted non-centrosymmetric structure. The band structure and DOS for the majority spins of FM PbMnO3showed no band gap at the Fermi level. However, a gap opens up at the Fermi level in minority spin channel suggesting that it could be a half-metal and a potential spintronic candidate.

scholarly journals Ground State of the H3+ Molecular Ion: Physics Behind

2013 ◽  
Vol 117 (39) ◽  
pp. 10119-10128 ◽  
Author(s):  
A. V. Turbiner ◽  
J. C. Lopez Vieyra
Keyword(s):  
Ground State ◽  
Molecular Ion

A Density Functional Study of Structures and Vibrations of Ta3O and Ta3O−

2005 ◽  
Vol 1 (4) ◽  
pp. 164-171 ◽  
Author(s):  
Patrizia Calaminici ◽  
Roberto Flores–Moreno ◽  
Andreas M. Köster
Keyword(s):  
Ground State ◽  
Photoelectron Spectroscopy ◽  
Density Functional ◽  
Equilibrium Structure ◽  
Negative Ion ◽  
Functional Study ◽  
Experimental Prediction ◽  
Extra Electron ◽  
Ground State Structures ◽  
Good Agreement

Density functional calculations of neutral and anionic tantalum trimer monoxide are presented. The calculations were performed employing scalar quasi–relativistic effective core potentials. Different isomers of Ta3O and Ta3O- were studied in order to determinethe ground state structures. For both systems a planar C2vstructure with an edge-boundoxygen atom was found as ground state. Equilibrium structure parameters, harmonic frequencies, adiabatic electron affinity and Kohn-Sham orbital diagrams are reported. The calculated values are in good agreement with the available experimental data obtained from negative ion photoelectron spectroscopy. The correlation diagram between the neutral and anionic Ta3O shows that, in agreement with the experimental prediction, the extra electron in the anionic system occupies a nonbonding orbital.

scholarly journals f-Electron and Magnetic Ordering Effects in Nickelates LaNiO2 and NdNiO2: Remarkable Role of The Cuprate-Like 3dx2-y2 Band

2020 ◽  
Author(s):  
Jianwei Sun ◽  
Ruiqi Zhang ◽  
Christopher Lane ◽  
Bahadur Singh ◽  
Johannes Nokelainen ◽  
...  
Keyword(s):  
Ground State ◽  
Exchange Coupling ◽  
Density Functional ◽  
High Temperature Superconductivity ◽  
Parent Compound ◽  
Magnetic Ordering ◽  
Striking Similarity ◽  
Infinite Layer ◽  
Open Questions

Abstract Recent discovery of superconductivity in the doped infinite-layer nickelates has renewed interest in understanding the nature of high-temperature superconductivity more generally. The low-energy electronic structure of the parent compound NdNiO2, the role of electronic correlations in driving superconductivity, and the possible relationship betweeen the cuprates and the nickelates are still open questions. Here, by comparing LaNiO2 and NdNiO2 systematically within a parameter free density functional framework, all-electron first-principles framework, we reveal the role Nd 4f-electrons in shaping the ground state of pristine NdNiO2. Strong similarities are found between the electronic structures of LaNiO2 and NdNiO2, except for the effects of the 4f-electrons. Hybridization between the Nd 4f and Ni 3d orbitals is shown to significantly modify the Fermi surfaces of various magnetic states. In contrast, the competition between the magnetically ordered phases depends mainly on the gaps in the Ni dx2-y2 band, so that the ground state in LaNiO2 and NdNiO2 turns out to be striking similarity to that of the cuprates. The d - p band-splitting is found to be much larger while the intralayer 3d ion-exchange coupling is smaller in the nickelates compared to the cuprates. Our estimated value of the on-site Hubbard U is similar to that in the cuprates, but the value of the Hund's coupling JH is found to be sensitive to the Nd magnetic moment. The exchange coupling J in NdNiO2 is only half as large as in the curpates, which may explain why Tc in the nickelates is half as large as the cuprates.

scholarly journals GGA/PBE study of the spin isomers of Fe34,40, Co23,34, and Co12Cu Clusters with Selected Geometries

2017 ◽  
Vol 56 (3) ◽  
Author(s):  
Faustino Aguilera-Granja ◽  
Andrés Vega ◽  
Luis Carlos Balbás
Keyword(s):  
Ground State ◽  
Density Functional ◽  
Energy Difference ◽  
Many Body ◽  
Generalized Gradient ◽  
Structural Isomers ◽  
Functional Theory ◽  
Ferromagnetic Ground State ◽  
Spin Isomers ◽  
Pseudo Potential

In a recent beam deflecting experiment was found that high and low spin states of pure Fe<sub>n</sub> and Co<sub>n</sub> clusters with <em>n</em> ≤ 300 atoms coexist at cryogenic temperatures. In this work we have studied the high spin (HS) and low spin (LS) states of several structural isomers of Co<sub>23</sub>, Co<sub>34</sub>, Fe<sub>34</sub>, and Fe<sub>40</sub> using the generalized gradient approximation (GGA) to density functional theory as implemented in the first-principles pseudo-potential code SIESTA. The calculated energy difference between these HS and LS isomers is not consistent with the observed coexistence, which can be due to an insufficient account of many body correlation effects in the GGA description, or to unknown isomer structures of these clusters. We have calculated within the same tools the magnetic isomers of Co<sub>12</sub>Cu cluster aimed to re-visit a former DFT prediction of an anti-ferromagnetic ground state. We find, however, a ferromagnetic ground state as expected on physical grounds. Our results exemplify the difficulties of the current DFT approaches to describe the magnetic properties of transition metal systems.

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