Ultra-fast computation of electronic spectra for large systems by tight-binding based simplified Tamm-Dancoff approximation (sTDA-xTB)

2016 ◽  
Vol 145 (5) ◽  
pp. 054103 ◽  
Author(s):  
Stefan Grimme ◽  
Christoph Bannwarth
Keyword(s):  
Electronic Spectra ◽  
Tight Binding ◽  
Fast Computation ◽  
Large Systems

A Novel Scheme for Accurate Md Simulations of Large Systems

1997 ◽  
Vol 491 ◽  
Author(s):  
Alessandro De Vita ◽  
Roberto Car
Keyword(s):  
Electronic Structure ◽  
Material Science ◽  
Tight Binding ◽  
Md Simulations ◽  
Model Potential ◽  
Black Box ◽  
Linear Scaling ◽  
Large Systems ◽  
Large Material ◽  
Ab Initio Models

ABSTRACTWe present a simple and informationally efficient approach to electronic-structure-based simulations of large material science systems. The algorithm is based on a flexible embedding scheme, in which the parameters of a model potential are fitted at run time to some precise information relevant to localised portions of the system. Such information is computed separately on small subsystems by electronic-structure “black box” subprograms, e.g. based on tight-binding and/or ab initio models. The scheme allows to enforce electronic structure precision only when and where needed, and to minimise the computed information within a desired accuracy, which can be systematically controlled. Moreover, it is inherently linear scaling, and highly suitable for modern parallel platforms, including those based on non-uniform processing. The method is demonstrated by performing computations of tight-binding accuracy on solid state systems in the ten thousand atoms size scale.

scholarly journals К модельному описанию электронного спектра графеноподобных Янус-структур

2022 ◽  
Vol 64 (2) ◽  
pp. 277
Author(s):  
С.Ю. Давыдов
Keyword(s):  
Electronic Spectra ◽  
Function Method ◽  
Hexagonal Lattice ◽  
Tight Binding ◽  
Mechanical Deformation ◽  
Two Dimensional ◽  
Binding Theory ◽  
Effective Masses ◽  
Magnetic States ◽  
Analytical Expressions

Model of C – AB – D Janus structure as the compound formed by the interacting through atoms А and В dimers А – С and В – D, where А and В atoms are in the sites of two-dimensional hexagonal lattice and C and D atoms are on the opposite sides from AB list is proposed. In the scope of tight-binding theory and Green’s function method general equation for the dispersion low is obtained. The particular cases of C – AА – D и А – AB – В compounds are considered and analytical expressions for their electronic spectra is fulfilled. The effect of the external mechanical deformation on the band parameters including effective masses is examined. Problem of the magnetic states in Janus compounds is discussed.

A Critical-Siphon Approach to Fastest Deadlock Controller for S3PR

2013 ◽  
pp. 269-295 ◽  
Author(s):  
Daniel Yuh Chao
Keyword(s):  
Optimal Control ◽  
Polynomial Complexity ◽  
Dynamic Reconfiguration ◽  
Fast Computation ◽  
Reachability Graph ◽  
Computational Burden ◽  
The Family ◽  
Large Systems

The authors developed a theory to show that exactly one monitor is required for the set of siphons in the family of 2-compound siphons and how to assign its initial markings. This avoids redundant monitors and the unnecessary associated computational burden. Neither reachability graph nor minimal siphon needs to be computed to achieve polynomial complexity—essential for large systems. This chapter redevelops the theory more formally and further applies this approach to two well-known S3PR to obtain a controller full or near maximally permissive, where Weighted Control (WC) arcs are nevertheless necessary to keep the controlled model maximally permissive. However, optimal control for siphons involving WC arcs are still under research. As many as possible for simpler structures are desired to reduce WC arcs. In addition, fast computation is important for dynamic reconfiguration situations. The authors develop a single theorem to identify the condition where WC places cannot be replaced by Ordinary Control (OC) arcs, while others can be replaced.

scholarly journals Interaction between chloride ions mediated by carbon nanotubes: a chemical attraction

2020 ◽  
Vol 24 (11-12) ◽  
pp. 3207-3214
Author(s):  
Fabiola Dominguez-Flores ◽  
Elizabeth Santos ◽  
Wolfgang Schmickler ◽  
Fernanda Juarez
Keyword(s):  
Density Functional ◽  
Tight Binding ◽  
Chem Phys ◽  
Chloride Ions ◽  
Electronic Density ◽  
Functional Theory ◽  
Covalent Component ◽  
Chemical Attraction ◽  
Large Systems ◽  
Effective Attraction

Abstract The interaction between two Cl− ions separated by the wall of a narrow carbon nanotube has been investigated by density functional theory (DFT) and by DFT-based tight binding (DFTB+). The direct Coulomb interaction between the ions is screened by the nanotube, no matter if the latter is conducting or semiconducting. The presence of the ions induces changes in the electronic density of states of the nanotube, which results in an effective attraction between the ions of the order of 0.2–0.3 eV. The interaction of the outside ions with the tube has a covalent component, when the two ions are near there is even a direct chemical attraction between the ions. In contrast to the effective attraction between two Li+ ions reported before (Juarez et al., Phys Chem Chem Phys 22:10,603, 2020), the effect cannot be explained in terms of physical concepts alone. DFTB+ performs well when compared with DFT, and lends itself to fast calculations for large systems.

scholarly journals A DFTB-Based Molecular Dynamics Investigation of an Explicitly Solvated Anatase Nanoparticle

2022 ◽  
Vol 12 (2) ◽  
pp. 780
Author(s):  
Dáire O’Carroll ◽  
Niall English
Keyword(s):  
Molecular Dynamics ◽  
Density Functional ◽  
Tight Binding ◽  
Static Properties ◽  
Additional Information ◽  
Water Layers ◽  
Observed Behaviour ◽  
Large Systems ◽  
High Degree ◽  
Structure Calculations

We performed a self-consistent charge density functional tight-binding molecular dynamics (SCC DFTB-MD) simulation of an explicitly solvated anatase nanoparticle. From the 2 ps trajectory, we were able to calculate both dynamic and static properties, such as the energies of interaction and the formation of water layers at the surface, and compare them to the observed behaviour reported elsewhere. The high degree of agreement between our simulation and other sources, and the additional information gained from employing this methodology, highlights the oft-overlooked viability of DFTB-based methods for electronic structure calculations of large systems.

A tight-binding method for the evaluation of the total energy of large systems

1995 ◽  
Vol 16 (2) ◽  
pp. 503-510 ◽  
Author(s):  
M. J. Mehl ◽  
D. A. Papaconstantopoulos ◽  
R. E. Cohen
Keyword(s):  
Total Energy ◽  
Tight Binding ◽  
Tight Binding Method ◽  
Large Systems
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