scholarly journals Plane-wave DFT-LDA calculation of the electronic structure and absorption spectrum of copper

2001 ◽  
Vol 64 (19) ◽  
Author(s):  
Andrea Marini ◽  
Giovanni Onida ◽  
Rodolfo Del Sole
Keyword(s):  
Absorption Spectrum ◽  
Electronic Structure ◽  
Plane Wave

Interstitial vs. Substitutional Metal Insertion in V2O5 as Post-Lithium Ion Battery Cathode: A Comparative GGA/GGA+U Study with Localized Bases

2020 ◽  
Author(s):  
Daniel Koch ◽  
Sergei Manzhos
Keyword(s):  
Electronic Structure ◽  
Plane Wave ◽  
Transition Metal Oxides ◽  
Reasonable Agreement ◽  
Correction Term ◽  
Lithium Ion ◽  
Generalized Gradient ◽  
Main Group Metals ◽  
Generalized Gradient Approximation ◽  
Metal Insertion

<p></p><p>The generalized gradient approximation (GGA) often fails to correctly describe the electronic structure and thermochemistry of transition metal oxides and is commonly improved using an inexpensive correction term with a scaling parameter <i>U</i>. We tune <i>U</i> to reproduce experimental vanadium oxide redox energetics with a localized basis and a GGA functional. We find the value for <i>U</i> to be significantly lower than what is generally reported with plane-wave bases, with the uncorrected GGA results being in reasonable agreement with experiments. We use this computational setup to calculate interstitial and substitutional <a>insertion energies of main group metals in vanadium pentoxide</a> and find <a>interstitial doping to be thermodynamically favored</a>.</p><p></p>

The Properties of a Na-Doped Twist Boundary in SrTiO3 from First Principles

2002 ◽  
Vol 751 ◽  
Author(s):  
Roope K. Astala ◽  
Paul D. Bristowe
Keyword(s):  
Electronic Structure ◽  
Grain Boundary ◽  
Plane Wave ◽  
First Principles ◽  
Driving Force ◽  
Chemical Potential ◽  
Twist Boundary ◽  
Atomic Displacements ◽  
Formation Energies ◽  
Oxygen Chemical Potential

ABSTRACTThe segregation of Nasr impurities to a Σ = 5 [001] twist boundary in SrTiO3 is studied using DFT-based plane-wave pseudopotential techniques. The formation energies of the impurities are calculated as a function of oxygen chemical potential and electron chemical potential. The results indicate a strong driving force for segregation to the boundary and that the Na impurities exhibit acceptor-like behaviour. The atomic displacements caused by the impurities are small both in the bulk and at the grain boundary. Based on the results a model is suggested in which Nasr segregation is driven by soft relaxation of the electronic structure.

Effect of intrinsic point defects on ZnO electronic structure and absorption spectra

2020 ◽  
Vol 34 (17) ◽  
pp. 2050147
Author(s):  
Yuqin Guan ◽  
Qingyu Hou ◽  
Danyang Xia
Keyword(s):  
Absorption Spectrum ◽  
Electronic Structure ◽  
Band Gap ◽  
Absorption Spectra ◽  
Point Defects ◽  
Formation Energy ◽  
Stable Structure ◽  
Impurity Level ◽  
Intrinsic Point Defects ◽  
Rich Condition

The effect of intrinsic point defects on the electronic structure and absorption spectra of ZnO was investigated by first-principle calculation. Among the intrinsic point defects in ZnO, oxygen vacancies [Formula: see text] and interstitial zinc [Formula: see text] have the lower formation energy and the more stable structure under zinc(Zn)-rich condition, whereas zinc vacancies [Formula: see text] and interstitial oxygen [Formula: see text] have the lower formation energy and the more stable structure under oxygen(O)-rich condition. The band gap of [Formula: see text] becomes narrow and the absorption spectrum has a redshift. In the visible region, the photo-excited electron transition of [Formula: see text] is graded from the valence band top to the impurity level and then to the conduction band bottom, showing the redshift of absorption spectrum of [Formula: see text] and explaining the reason of [Formula: see text] forming a deep impurity levels in ZnO. Moreover, the impurity energy level of [Formula: see text] coincides with the Fermi level, indicating the significant trap effect and the slow recombination of electrons and holes, which are conducive to the design and preparation of novel ZnO photocatalysts. The band gap of [Formula: see text] and [Formula: see text] broadened and the absorption spectrum showed blueshift, explaining the different values of the ZnO band gap width.

Vibrational Sampling and Solvent Effects on the Electronic Structure of the Absorption Spectrum of 2-Nitronaphthalene

2018 ◽  
Vol 14 (6) ◽  
pp. 3205-3217 ◽  
Author(s):  
J. Patrick Zobel ◽  
Moritz Heindl ◽  
Juan J. Nogueira ◽  
Leticia González
Keyword(s):  
Absorption Spectrum ◽  
Electronic Structure ◽  
Solvent Effects

scholarly journals First-principles study on the effects of N and Al doping on the mechanical properties and electronic structures of TiC

RSC Advances ◽  
2020 ◽  
Vol 10 (60) ◽  
pp. 36295-36302
Author(s):  
Zhinan Cao ◽  
Na Jin ◽  
Jinwen Ye ◽  
Xu Du ◽  
Ying Liu
Keyword(s):  
Mechanical Properties ◽  
Electronic Structure ◽  
Plane Wave ◽  
First Principles ◽  
Electronic Structures ◽  
First Principles Calculations ◽  
Al Doping ◽  
First Principles Study

First-principles calculations are carried out by DFT within the CASTEP plane wave code to investigate the mechanical properties and electronic structure of N and Al doped TiC.

scholarly journals Quantum simulation of chemistry with sublinear scaling in basis size

2019 ◽  
Vol 5 (1) ◽  
Author(s):  
Ryan Babbush ◽  
Dominic W. Berry ◽  
Jarrod R. McClean ◽  
Hartmut Neven
Keyword(s):  
Electronic Structure ◽  
Plane Wave ◽  
Quantum Chemistry ◽  
Plane Waves ◽  
Quantum Algorithm ◽  
Discretization Error ◽  
Rotating Frame ◽  
Interaction Picture ◽  
Basis Size ◽  
Oppenheimer Approximation

Abstract We present a quantum algorithm for simulating quantum chemistry with gate complexity $$\tilde {\cal{O}}(N^{1/3}\eta ^{8/3})$$ O ̃ ( N 1 ∕ 3 η 8 ∕ 3 ) where η is the number of electrons and N is the number of plane wave orbitals. In comparison, the most efficient prior algorithms for simulating electronic structure using plane waves (which are at least as efficient as algorithms using any other basis) have complexity $$\tilde {\cal{O}}(N^{8/3}{\mathrm{/}}\eta ^{2/3})$$ O ̃ ( N 8 ∕ 3 ∕ η 2 ∕ 3 ) . We achieve our scaling in first quantization by performing simulation in the rotating frame of the kinetic operator using interaction picture techniques. Our algorithm is far more efficient than all prior approaches when N ≫ η, as is needed to suppress discretization error when representing molecules in the plane wave basis, or when simulating without the Born-Oppenheimer approximation.

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