Combined tight-binding/DFT investigation of the electronic structure of triimine-platinum(II)/TCNQ extended stacks,

2009 ◽  
Vol 87 (7) ◽  
pp. 775-783 ◽  
Author(s):  
Hassan Rabaâ ◽  
Thomas R. Cundari ◽  
Mohammad A. Omary
Keyword(s):  
Electronic Structure ◽  
Density Functional ◽  
Tight Binding ◽  
Negative Energy ◽  
Large Contribution ◽  
Redox Potentials ◽  
Absorption Bands ◽  
Metallic Behavior ◽  
Charge Delocalization ◽  
Donor Acceptor

. The [Pt(tbtrpy)(X)][TCNQ] (X = OH or SH) complexes form sandwich stacks with nitrile acceptors leading to extended-chain supramolecular assemblies, tbtrpy = 4,4′,4″-tert-Bu3-2,2′:6′,2″-terpyridine. Calculations with the extended Hückel tight-binding (EHTB) method are performed upon crystalline {[Pt (tbtrpy)(X)][TCNQ]}∞ species to analyze their electronic structure and consequent properties, TCNQ = 7,7,8,8-tetracyanoquinodimethane. The donor/acceptor extended chains in the solid state are predicted to exhibit metallic behavior with a large contribution from π and π* bands of TCNQ to the valence and conduction bands, respectively. Moreover, the valence band moves upward (i.e., to a less negative energy) for X = SH as compared to X = OH. Density functional theory (DFT) calculations suggest that this is due to large thiolate character in the HOMO of the square-planar donor complex, which also supports the experimental assignment of the electronic absorption bands and redox potentials. Calculations of infrared (νCN bands of TCNQ) and structural (CC bond lengths within TCNQ) data explain the metallic behavior of the stacks in terms of charge delocalization, leading to fractionally-charged species of the form [Pt(tbtrpy)X](1+δ)+[TCNQ](1+δ)- with δ > 0 and a greater δ value for X = SH vs OH.

scholarly journals A quantitative evaluation of computational methods to accelerate the study of alloxazine-derived electroactive compounds for energy storage

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Qi Zhang ◽  
Abhishek Khetan ◽  
Süleyman Er
Keyword(s):  
Energy Storage ◽  
Density Functional ◽  
Tight Binding ◽  
Computational Cost ◽  
Redox Potentials ◽  
Storage Compounds ◽  
Computational Screening ◽  
Chemical Descriptor ◽  
Lowest Unoccupied Molecular Orbital ◽  
Semi Empirical

AbstractAlloxazines are a promising class of organic electroactive compounds for application in aqueous redox flow batteries (ARFBs), whose redox properties need to be tuned further for higher performance. High-throughput computational screening (HTCS) enables rational and time-efficient study of energy storage compounds. We compared the performance of computational chemistry methods, including the force field based molecular mechanics, semi-empirical quantum mechanics, density functional tight binding, and density functional theory, on the basis of their accuracy and computational cost in predicting the redox potentials of alloxazines. Various energy-based descriptors, including the redox reaction energies and the frontier orbital energies of the reactant and product molecules, were considered. We found that the lowest unoccupied molecular orbital (LUMO) energy of the reactant molecules is the best performing chemical descriptor for alloxazines, which is in contrast to other classes of energy storage compounds, such as quinones that we reported earlier. Notably, we present a flexible in silico approach to accelerate both the singly and the HTCS studies, therewithal considering the level of accuracy versus measured electrochemical data, which is readily applicable for the discovery of alloxazine-derived organic compounds for energy storage in ARFBs.

Electronic Structure and Ferromagnetic Properties of Doped Calcium Sulfide Ca1−xTMxS (TM = V, Cr and Co)

SPIN ◽  
2020 ◽  
Vol 10 (02) ◽  
pp. 2050013 ◽  
Author(s):  
Amina Aiche ◽  
Abdelkader Tadjer ◽  
Hadj Moulay Ahmed Mazouz ◽  
Bendouma Doumi ◽  
Houari Khachai
Keyword(s):  
Magnetic Properties ◽  
Electronic Structure ◽  
Density Functional ◽  
Double Exchange ◽  
Ferromagnetic State ◽  
Spin Splitting ◽  
Full Potential ◽  
Generalized Gradient ◽  
Metallic Behavior ◽  
Half Metallic

The electronic structure and magnetic properties of diluted Ca[Formula: see text]TMxS (TM[Formula: see text][Formula: see text][Formula: see text]V, Cr and Co) in the rocksalt structure at concentrations [Formula: see text], 0.125 and 0.25 were studied using the full-potential linearized augmented plane wave approximation of the density functional theory with the Wu-Cohen generalized gradient approximation (WC-GGA) and the Tran–Blaha-modified Becke–Johnson (TB-mBJ) potential. Features such as lattice constant, bulk modulus, spin-polarized band structures, total and local densities of states and magnetic properties have been computed. The electronic structure show that Ca[Formula: see text](V, Cr)xS at all the studied concentrations and the diluted Ca[Formula: see text]CoxS with [Formula: see text] compounds are half-metallic ferromagnets with spin polarization of 100%. The calculated total magnetic moments for Ca[Formula: see text]VxS and Ca[Formula: see text]CoxS show the same integer value of 3[Formula: see text][Formula: see text] per formula unit and Ca[Formula: see text]CrxS exhibit a total magnetic moment of 4[Formula: see text][Formula: see text], which confirm the half-metallic behavior of these compounds. We also calculated the values of the band edge spin splitting of the valence and conduction bands and the exchange constants. We have found that the ferromagnetic state is stable by the p-d exchange associated with the double-exchange mechanism. The diluted Ca[Formula: see text](V,Cr,Co)xS are found to be new promising candidates for spintronic applications.

Computational studies of energetics, electronic structure, and vibrational spectra of PETN nanoparticles

2021 ◽  
Vol 99 (1) ◽  
pp. 63-71
Author(s):  
Qiannan Ma ◽  
Weihua Zhu
Keyword(s):  
Electronic Structure ◽  
Vibrational Spectra ◽  
Density Functional ◽  
Solid Phase ◽  
Tight Binding ◽  
High Energy ◽  
Pentaerythritol Tetranitrate ◽  
Energy Bands ◽  
Extra Energy ◽  
The Stability

The density functional tight binding method was used to explore the energetics, electronic structure, and vibrational spectra of pentaerythritol tetranitrate (PETN) nanoparticles (NPs). The surface energy of the PETN NP is anisotropic and its extra energy decreases with the increase of size. The energy bands of the NPs are significantly expanded and the band gaps are narrowed, thus reducing the stability due to nanometer size effect. The surface of the NP is mainly covered by the NO2 group. The high-energy surface may play a role in triggering chemical decomposition. The vibration frequencies of the PETN NPs present a wider distribution than those of the gas and solid phase PETN, which will increase the probability of energy transfer to the molecules in the system and promote the decomposition of PETN. Our results provide a basic understanding from a molecular perspective to the energy properties of nano explosives.

scholarly journals A Protocol for Fast Prediction of Electronic and Optical Properties of Donor–Acceptor Polymers Using Density Functional Theory and the Tight-Binding Method

2019 ◽  
Vol 123 (23) ◽  
pp. 4980-4989 ◽  
Author(s):  
Murat Mesta ◽  
Jin Hyun Chang ◽  
Suranjan Shil ◽  
Kristian S. Thygesen ◽  
Juan Maria Garcia Lastra
Keyword(s):  
Density Functional Theory ◽  
Optical Properties ◽  
Density Functional ◽  
Tight Binding ◽  
Functional Theory ◽  
Electronic And Optical Properties ◽  
Tight Binding Method ◽  
Donor Acceptor ◽  
Fast Prediction

Density functional tight binding study of β-Ga2O3: Electronic structure, surface energy, and native point defects

2019 ◽  
Vol 150 (17) ◽  
pp. 174706 ◽  
Author(s):  
Jonghoon Lee ◽  
Sabyasachi Ganguli ◽  
Ajit K. Roy ◽  
Stefan C. Badescu
Keyword(s):  
Electronic Structure ◽  
Surface Energy ◽  
Point Defects ◽  
Density Functional ◽  
Tight Binding ◽  
Binding Study ◽  
Native Point Defects ◽  
Structure Surface

scholarly journals Density functional study of the electronic structure of dye-functionalized fullerenes and their model donor-acceptor complexes containing P3HT

2016 ◽  
Vol 144 (14) ◽  
pp. 144304 ◽  
Author(s):  
Tunna Baruah ◽  
Amanda Garnica ◽  
Marina Paggen ◽  
Luis Basurto ◽  
Rajendra R. Zope
Keyword(s):  
Electronic Structure ◽  
Density Functional ◽  
Functional Study ◽  
Density Functional Study ◽  
Functionalized Fullerenes ◽  
Donor Acceptor

ELECTRONIC STRUCTURE CALCULATIONS ON MoTe2 WITH ROTATED PLANES

2005 ◽  
Vol 19 (26) ◽  
pp. 3933-3943
Author(s):  
A. TLAHUICE ◽  
E. FLORES ◽  
D. H. GALVÁN
Keyword(s):  
Electronic Structure ◽  
Diffraction Pattern ◽  
Tight Binding ◽  
Electronic Structure Calculations ◽  
Experimental Measurements ◽  
Metallic Behavior ◽  
Tight Binding Method ◽  
Total Energies ◽  
Structure Calculations ◽  
Good Agreement

Electronic structure calculations have been carried out using Extended Hückel tight-binding method for 2 H — MoTe 2 for the cases both unrotated and with rotated planes. It has been found that relative rotations of the tellurium layers ranging from 5 to 16 degrees have the same total energies and total energies/atom as the unrotated structure. Moreover, an increased in metallic behavior has been observed, as long as the degrees of rotated planes are increased. Finally, good agreement has been found among previous experimental measurements in the diffraction pattern of irradiated MoTe 2 and our calculated 5, 6 and 7 degrees of rotations.

Modeling carbon nanostructures with the self-consistent charge density-functional tight-binding method: Vibrational spectra and electronic structure of C28, C60, and C70

2006 ◽  
Vol 125 (21) ◽  
pp. 214706 ◽  
Author(s):  
Henryk A. Witek ◽  
Stephan Irle ◽  
Guishan Zheng ◽  
Wibe A. de Jong ◽  
Keiji Morokuma
Keyword(s):  
Electronic Structure ◽  
Charge Density ◽  
Vibrational Spectra ◽  
Carbon Nanostructures ◽  
Density Functional ◽  
Tight Binding ◽  
The Self ◽  
Self Consistent ◽  
Tight Binding Method

scholarly journals LSDA+U APPROXIMATION-BASED ANALYSIS OF THE ELECTRONIC STRUCTURE OF CeFeGe3

2006 ◽  
Vol 20 (03) ◽  
pp. 287-301 ◽  
Author(s):  
E. CHIGO-ANOTA ◽  
A. FLORES-RIVEROS ◽  
J. F. RIVAS-SILVA
Keyword(s):  
Electronic Structure ◽  
Density Functional ◽  
Correction Term ◽  
Tight Binding ◽  
Electronic Structure Calculations ◽  
Local Spin Density Approximation ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Sphere Approximation ◽  
Structure Calculations

We perform ab initio electronic structure calculations of the intermetallic compound CeFeGe 3 by means of the Tight Binding Linear Muffin-Tin Orbitals-Atomic Sphere Approximation (TB-LMTO-ASA) within the Local Spin Density Approximation containing the so-called Hubbard correction term ( LSDA+U SIC), using the Stuttgart's TB (Tight Binding)-LMTO-ASA code in the framework of the Density Functional Theory (DFT). At the LSDA-vBH level, our electronic structure calculations indicate an intermediate valence character compound whereas a DOS (density of states) analysis favors its metallic nature. We also study electronic correlation effects via the introduction of the U parameter on Ce and Fe , where a metallic and magnetic characters for this compound are found, along with certain features that may possibly be associated with a heavy fermion system.

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