scholarly journals Lithium Attachment to C60 and Nitrogen- and Boron-Doped C60: A Mechanistic Study

Materials ◽  
2019 ◽  
Vol 12 (13) ◽  
pp. 2136 ◽  
Author(s):  
Yingqian Chen ◽  
Chae-Ryong Cho ◽  
Sergei Manzhos
Keyword(s):  
Electronic Structure ◽  
Small Molecules ◽  
Lithium Ion ◽  
Single Atom ◽  
Mechanistic Study ◽  
Hybrid Functional ◽  
Generalized Gradient ◽  
Generalized Gradient Approximation ◽  
Boron Doped ◽  
P Type

Fullerene-based materials including C60 and doped C60 have previously been proposed as anodes for lithium ion batteries. It was also shown earlier that n- and p-doping of small molecules can substantially increase voltages and specific capacities. Here, we study ab initio the attachment of multiple lithium atoms to C60, nitrogen-doped C60 (n-type), and boron doped C60 (p-type). We relate the observed attachment energies (which determine the voltage) to changes in the electronic structure induced by Li attachment and by doping. We compare results with a GGA (generalized gradient approximation) functional and a hybrid functional and show that while they agree semi-quantitatively with respect to the expected voltages, there are qualitative differences in the electronic structure. We show that, contrary to small molecules, single atom n- and p-doping will not lead to practically useful modulation of the voltage–capacity curve beyond the initial stages of lithiation.

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>

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>

Effect of Chromium and Vanadium on Nanolayered Ternary Carbides: AB Initio Study

2009 ◽  
Vol 609 ◽  
pp. 239-242
Author(s):  
A.E. Merad ◽  
M.B. Kanoun
Keyword(s):  
Electronic Structure ◽  
Total Energy ◽  
Ab Initio ◽  
Structural Parameters ◽  
Ab Initio Study ◽  
Generalized Gradient ◽  
Generalized Gradient Approximation ◽  
Full Relaxation ◽  
Relaxation Procedure ◽  
Ternary Carbides

The Cr2AlC and V2AlC nanolayered ternary carbides are studied by performing APW-lo ab initio total energy calculations within the recent Wu-Cohen generalized gradient approximation GGA. Using full relaxation procedure of the volume and the atomic positions we obtained the structural parameters and electronic structure of the optimization hexagonal. Results were compared with the experimental ones. Interesting features are deduced. In fact, we have shown why these materials are conductors.

First principles study of the structural, electronic and optical properties of crystalline o-phenanthroline

2016 ◽  
Vol 30 (14) ◽  
pp. 1650077 ◽  
Author(s):  
Hajar Nejatipour ◽  
Mehrdad Dadsetani
Keyword(s):  
Optical Properties ◽  
Electronic Structure ◽  
First Principles ◽  
Binding Energies ◽  
Many Body ◽  
Generalized Gradient ◽  
Generalized Gradient Approximation ◽  
Independent Particle ◽  
Excitonic Effects ◽  
Comprehensive Study

In a comprehensive study, structural properties, electronic structure and optical response of crystalline o-phenanthroline were investigated. Our results show that in generalized gradient approximation (GGA) approximation, o-phenanthroline is a direct bandgap semiconductor of 2.60 eV. In the framework of many-body approach, by solving the Bethe–Salpeter equation (BSE), dielectric properties of crystalline o-phenanthroline were studied and compared with phenanthrene. Highly anisotropic components of the imaginary part of the macroscopic dielectric function in o-phenanthroline show four main excitonic features in the bandgap region. In comparison to phenanthrene, these excitons occur at lower energies. Due to smaller bond lengths originated from the polarity nature of bonds in presence of nitrogen atoms, denser packing, and therefore, a weaker screening effect, exciton binding energies in o-phenanthroline were found to be larger than those in phenanthrene. Our results showed that in comparison to the independent-particle picture, excitonic effects highly redistribute the oscillator strength.

scholarly journals Electronic Structure Calculations of A2Ti2O7(A = Dy, Ho, and Y)

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
H. Y. Xiao
Keyword(s):  
Electronic Structure ◽  
Strong Interaction ◽  
Electronic Structures ◽  
Coulomb Repulsion ◽  
Electronic Structure Calculations ◽  
Generalized Gradient ◽  
Generalized Gradient Approximation ◽  
Structural And Electronic Properties ◽  
Structure Calculations ◽  
Irradiation Resistance

Ab initiocalculations have been performed on titanate pyrochlores A2Ti2O7(A = Dy, Ho, and Y) to investigate their electronic structures. The generalized gradient approximation (GGA) +Uformalism has been used to correct the strong onsite Coulomb repulsion between the localized 4f electrons. The effects of effectiveUvalues on the structural and electronic properties of A2Ti2O7(A = Dy, Ho, and Y) have been discussed. It is shown that Dy2Ti2O7and Ho2Ti2O7exhibit different electronic structures from Y2Ti2O7. The strong interaction between Dy and Ho 4f electrons and O 2p orbitals may increase the covalency of〈Dy–O〉and〈Ho–O〉bonds and decrease their irradiation resistance.

Structural, optoelectronic and elastic properties of quaternary perovskites CaPd3B4O12 (B = Ti, V)

2019 ◽  
Vol 33 (19) ◽  
pp. 1950212 ◽  
Author(s):  
Shahid Mehmood ◽  
Zahid Ali ◽  
Zainab Hashmi ◽  
Sahar Khan
Keyword(s):  
Density Functional ◽  
Dielectric Material ◽  
Structural Parameters ◽  
Wide Bandgap ◽  
Spin Orbit Coupling ◽  
Hybrid Functional ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Generalized Gradient Approximation ◽  
Reported Data

Perovskites CaPd3B4O[Formula: see text] (B = Ti, V) are studied theoretically using generalized gradient approximation (GGA), GGA-modified Becke–Johnson (GGA-mBJ), GGA with spin-orbit coupling (GGA + SOC) and hybrid functional (HF) in the domain of density functional theory (DFT). The estimated structural parameters are reliable with the experimentally reported data. Cohesive energy and enthalpy show that these compounds are stable thermodynamically. Bonding nature makes known that the chemical bond between Ca/Ti–O is ionic, Pd/V–O is covalent and Ti/V–Ti/V is metallic. The mechanical properties show that these compounds are stable, elastically anisotropic and ductile in nature. CaPd3Ti4O[Formula: see text] is a 2.94 eV direct-wide bandgap semiconductor through GGA-mBJ and consistent with experiments. The optical properties show that CaPd3Ti4O[Formula: see text] is a good dielectric material. The dense electronic states and the wide-gap semiconductor nature of CaPd3Ti4O[Formula: see text] suggest that it can be used as a good thermoelectric material.

First Principle Study on Electronic Structure of Nanocrystalline BaTiO3 Ceramics

2007 ◽  
Vol 336-338 ◽  
pp. 2510-2512
Author(s):  
Xiang Yun Deng ◽  
Long Tu Li ◽  
Xiao Hui Wang ◽  
Zhi Lun Gui
Keyword(s):  
Electronic Structure ◽  
Partial Density ◽  
Full Potential ◽  
Generalized Gradient ◽  
Augmented Plane Wave ◽  
Plane Wave Method ◽  
Generalized Gradient Approximation ◽  
Augmented Plane Wave Method ◽  
Nanocrystalline Batio3 Ceramics ◽  
Linearized Augmented Plane Wave

The full potential linearized augmented plane wave method within the generalized gradient approximation was used to calculate electronic structure of nanocrystalline BaTiO3 ceramics. We calculated the total and partial density of states of 50 nm BaTiO3 ceramics. The results show that the atoms distribution of nanograin BaTiO3 ceramics is different from those of coarse BaTiO3 ceramics. It is also revealed that the hybridization between Ti 3d and O 2p is very strong, which is very important to the ferroelectric stability of nanocrystalline BaTiO3 ceramics.

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