scholarly journals Opto-Electronic Study of SiC Polytypes: Simulation with Semi-Empirical Tight-Binding Approach

10.5772/24124 ◽  
2011 ◽  
Author(s):  
Amel Laref ◽  
Slimane Laref
Keyword(s):  
Tight Binding ◽  
Semi Empirical

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.

Thermal Properties of Divalent Metal Oxides: CaO as a Prototype

2013 ◽  
Vol 209 ◽  
pp. 190-193
Author(s):  
Nisarg K. Bhatt ◽  
Brijmohan Y. Thakore ◽  
P.R. Vyas ◽  
A.Y. Vahora ◽  
Asvin R. Jani
Keyword(s):  
Density Functional ◽  
Tight Binding ◽  
Mean Field ◽  
Field Potential ◽  
Theoretical Data ◽  
Test Case ◽  
Generalized Gradient ◽  
Core Electrons ◽  
Vibrational Free Energy ◽  
Semi Empirical

Commonly employed quasiharmonic approximation (QHA) is inadequate to account for intrinsic anharmonism such as phonon-phonon interaction, vacancy contribution, etc. Though anharmonic contributions are important at high temperatures and low pressure, complete ab initio calculations are scanty due largely to laborious computational requirements. Nevertheless, some simple semi-empirical schemes can be used effectively to incorporate the anharmonism. In this regards, in the present study we have proposed a simple computational scheme to include the effect of vacancy directly into the description within the mean-field potential approach, which calculates vibrational free energy of ions. Validity of the scheme is verified by taking calcium oxide as a test case. Equilibrium properties at (T,P) = (0,0) condition is obtained within the tight-binding second-moment approximation (TB-SMA), whose parameters were determined through first principles density functional theory. Kohn-Sham equations for core electrons were solved using ultrasoft plane-wave pseudopotential employing the generalized gradient approximation for exchange and correlation. Present findings for thermal expansion and high-T EOS clearly show perceptible improvement over the case when vacancy contribution was not included. Some related thermodynamic properties are also calculated and compared with the available experimental and theoretical data.

Transfer Integrals and Band Structures in (Et)2X Salts

1989 ◽  
Vol 173 ◽  
Author(s):  
Oliver H. Leblanc ◽  
Margaret L. Blohm ◽  
Richard P. Messmer
Keyword(s):  
Low Temperature ◽  
Nearest Neighbor ◽  
Spherical Wave ◽  
Tight Binding ◽  
Ab Initio Method ◽  
Energy Bands ◽  
Hubbard Hamiltonian ◽  
Transfer Integrals ◽  
Semi Empirical ◽  
Very Low Temperature

ABSTRACTTransfer integrals (tij) between pairs of nearest neighbor ET molecules were calculated by an ab initio method. Tight-binding one-electron energy bands constructed from the tij are similar to those previously calculated by Mori and by Whangbo and their coworkers by semi-empirical, extended Hückel methods, but quite different from those found by Kübler et al. in β-(ET)2I3 using the augmented spherical wave (ASW) method. However, all these band models are suspect. The Hubbard on-site repulsion parameter U is estimated to be about twice the band widths, indicating that a full treatment of the Hubbard hamiltonian is needed. Also, polaron effects appear to control transport except at very low temperature.

Determination of the high c/a ratio of hexagonal metals with a semi-empirical tight-binding method

2000 ◽  
Vol 17 (2-4) ◽  
pp. 249-254 ◽  
Author(s):  
A Béré ◽  
J Chen ◽  
A Hairie ◽  
G Nouet ◽  
E Paumier
Keyword(s):  
Tight Binding ◽  
Tight Binding Method ◽  
Semi Empirical ◽  
Hexagonal Metals

scholarly journals Density functional tight binding: values of semi-empirical methods in an ab initio era

2014 ◽  
Vol 16 (28) ◽  
pp. 14368-14377 ◽  
Author(s):  
Qiang Cui ◽  
Marcus Elstner
Keyword(s):  
Density Functional Theory ◽  
Ab Initio ◽  
Density Functional ◽  
Tight Binding ◽  
Empirical Methods ◽  
Functional Theory ◽  
Hartree Fock ◽  
Semi Empirical

Semi-empirical (SE) methods are derived from Hartree–Fock (HF) or Density Functional Theory (DFT) by neglect and approximation of electronic integrals.

Semi-empirical tight binding modelling of CdSTe/CdTe, ZnSSe/ZnSe and ZnSSe/ CdSe heterostructures

2009 ◽  
Vol 517 (7) ◽  
pp. 2431-2437 ◽  
Author(s):  
Özden Akinci ◽  
H. Hakan Gürel ◽  
Hilmi Ünlü
Keyword(s):  
Tight Binding ◽  
Semi Empirical

Basal stacking faults and (10&1macr;2) twin energies by a semi-empirical tight-binding method for zinc and cadmium

2004 ◽  
Vol 241 (11) ◽  
pp. 2482-2488 ◽  
Author(s):  
A. Béré ◽  
J. Chen ◽  
A. Hairie ◽  
G. Nouet ◽  
E. Paumier
Keyword(s):  
Tight Binding ◽  
Stacking Faults ◽  
Tight Binding Method ◽  
Semi Empirical
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