The tight-binding bond model

Sutton, A. P.; Finnis, Michael W.; Pettifor, D. G.; Ohta, Y.

doi:10.1088/0022-3719/21/1/007

Cited by 442 publications

(242 citation statements)

References 49 publications

Supporting

Mentioning

240

Contrasting

Order By: Relevance

“…2 to decrease almost monotonically with the number of d electrons for the solute atoms. In tight-binding, canonical d-band models of the electronic structure of hcp transition metals [55][56][57][58] the bond order between neighbors within and out of the basal plane is decomposed into ddσ, ddπ and ddδ twocenter hopping-integral contributions. Bonding contributions between neighbors in the basal plane and out of the basal plane are denoted by σ 1 , π 1 , δ 1 and σ 2 , π 2 , δ 2 , respectively.…”

Section: Discussionmentioning

confidence: 99%

“…Bonding contributions between neighbors in the basal plane and out of the basal plane are denoted by σ 1 , π 1 , δ 1 and σ 2 , π 2 , δ 2 , respectively. Starting at half band filling, the σ 1 and σ 2 bonding weakens with a decrease in the number of d electrons, whereas the in-plane bonding π 1 is enhanced while the π 2 bonding levels off (the δ bonding is relatively insignificant) 55 . This implies that the bonding in the basal plane gets reinforced with respect to the bonding out of the basal plane with decreasing band filling, which is qualitatively consistent with our finding that the c/a ratio of Re increases when alloyed with TM solutes to the left in the periodic table.…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

First-principles study of the structural and elastic properties of rhenium-based transition-metal alloys

et al. 2012

View full text Add to dashboard Cite

Structural, energetic and elastic properties of hexagonal-close-packed rhenium-based transitionmetal alloys are computed by density-functional theory. The practical interest in these materials stems from the attractive combination of mechanical properties displayed by rhenium for structural applications requiring the combination of high melting temperature and low-temperature ductility. Single-crystal elastic constants, atomic volumes, axial c/a ratios, and dilute heats of solution for Re-X alloys are computed, considering all possible transition-metal solute species X. Calculated elastic constants are used to compute values of a commonly considered intrinsic-ductility parameter K/G, where K is the bulk modulus and G denotes the Voigt average of the shear modulus, as well as the anisotropies in the Young's modulus and shear modulus. The calculated properties show clear trends as a function of d-band filling, which can be rationalized through tight-binding theory. The results indicate that solutes to the left of rhenium in the periodic table show a tendency to increase the intrinsic ductility parameter, a trend that correlates with an increase of the c/a ratio towards the ideal value associated optimal close packing. The Young's modulus shows a trend towards increasing isotropy with alloying of solutes X to the left of Re, while the shear modulus shows the opposite trend but with an overall weaker dependence on solute additions.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

First-principles study of the structural and elastic properties of rhenium-based transition-metal alloys

et al. 2012

View full text Add to dashboard Cite

show abstract

“…Therefore, we coarse-grain the description of the electronic structure and continue our study with the tight-binding bond model [20] that has proven to be sufficient for identifying structural trends (see e.g. Refs.…”

Section: Tight-binding Approximation and Bond-order Potentialmentioning

confidence: 99%

Modeling Topologically Close-Packed Phases in Superalloys: Valence-Dependent Bond-Order Potentials Based on Ab-Initio Calculations

Hammerschmidt¹,

Seiser²,

Drautz³

et al. 2008

Superalloys 2008 (Eleventh International Symposium)

View full text Add to dashboard Cite

Refractory elements are used in Ni-based superalloys to increase creep resistance (Mo, Re, W) and to retard the coarsening of the γ' phase (Re). At high concentrations of refractory elements precipitation of topologically closepacked (tcp) phases [1] is detrimental to the creep properties of the alloys. A more detailed understanding of the formation kinetics and thermodynamic stability of tcp phases will therefore be beneficial for the design of the next generation superalloys. Atomistic modeling of tcp stability with interatomic potentials requires to go beyond the second-moment approximation to the electronic density of states by including up to at least the sixth moment [2]. We have developed an analytic bond-order potential (BOP) that systematically takes into account higher moment contributions to the density of states and depends explicitly on the valence of the transition-metal elements [3]. For the parameterization of the new BOP, we performed extensive density functional theory (DFT) calculations of elemental and binary compound phases of Ni, the technologically important alloying element Cr, and the refractory metals Mo, Re, and W. We will discuss the structural trends of the DFT calculations, compare to the predictions of the analytic BOP and report on our progress on the parameterization of the analytic BOP for the Re-W system. This work is part of the EPSRC-funded collaborative multi-scale project 'Alloys by Design'.

show abstract

“…15,16 Among other benefits this allows a more ready extension to highly correlated electron systems. 17,18 If the Hohenberg-Kohn total energy 19 is expanded to second order in the difference δρ between the self consistent density and some trial, input density ρ in (r), one obtains [20][21][22] E (2) = n occ.…”

Section: Self Consistent Polarizable Ion Tight Binding (Pitb)mentioning

confidence: 99%

Universal tight binding model for chemical reactions in solution and at surfaces. I. Organic molecules

Sheppard

Lozovoi

Pashov

et al. 2014

The Journal of Chemical Physics

View full text Add to dashboard Cite

Articles you may be interested inAs is now well established, a first order expansion of the Hohenberg-Kohn total energy density functional about a trial input density, namely, the Harris-Foulkes functional, can be used to rationalize a non self consistent tight binding model. If the expansion is taken to second order then the energy and electron density matrix need to be calculated self consistently and from this functional one can derive a charge self consistent tight binding theory. In this paper we have used this to describe a polarizable ion tight binding model which has the benefit of treating charge transfer in point multipoles. This admits a ready description of ionic polarizability and crystal field splitting. It is necessary in constructing such a model to find a number of parameters that mimic their more exact counterparts in the density functional theory. We describe in detail how this is done using a combination of intuition, exact analytical fitting, and a genetic optimization algorithm. Having obtained model parameters we show that this constitutes a transferable scheme that can be applied rather universally to small and medium sized organic molecules. We have shown that the model gives a good account of static structural and dynamic vibrational properties of a library of molecules, and finally we demonstrate the model's capability by showing a real time simulation of an enolization reaction in aqueous solution.In two subsequent papers, we show that the model is a great deal more general in that it will describe solvents and solid substrates and that therefore we have created a self consistent quantum mechanical scheme that may be applied to simulations in heterogeneous catalysis. © 2014 AIP Publishing LLC.

show abstract

The tight-binding bond model

Cited by 442 publications

References 49 publications

First-principles study of the structural and elastic properties of rhenium-based transition-metal alloys

First-principles study of the structural and elastic properties of rhenium-based transition-metal alloys

Modeling Topologically Close-Packed Phases in Superalloys: Valence-Dependent Bond-Order Potentials Based on Ab-Initio Calculations

Universal tight binding model for chemical reactions in solution and at surfaces. I. Organic molecules

Contact Info

Product

Resources

About