# Tight-binding theory of force constant models

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The matrix of the kinetic energy operator can be divided into two components, one of which is equivalent to the matrix of a function so that it is effectively local. This decomposition is basis-set dependent and is particularly simple when equidensity orbitals are used. It is shown that for a...

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Motivated by recent developments in the field of one-dimensional topological superconductors, we investigate the topological properties of s-matrix of generic superconducting junctions where dimension should not play any role. We argue that for a finite junction the s-matrix is always...

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A general expression is obtained for the exchange interaction energy of an electron in a semiconductor for arbitrary degree of degeneracy of an electron gas. The single-particle exchange energy is expressed in terms of an integral function that depends only on the ratio of the Fermi energy,...

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In part I, both the arrow diagram (AD) and expanded AD decompositions of the antisymmetrization operator A for an N-electron system with wave function represented by the product of mutually nonorthogonal group functions have been considered. Based on them, new diagrams for decompositions of...

- Basis set dependence of the locality of the kinetic energy operator. Hoch, Douglas E.; Harriman, John E. // Journal of Chemical Physics;4/15/1996, Vol. 104 Issue 15, p5898
We have analyzed the locality of matrices of the kinetic energy operator in even-tempered Gaussian and Slater-type (STO) bases, as well as in several three-dimensional, one-dimensional, and pseudo-one-dimensional basis sets of orthogonal polynomials and trigonometric functions. We find that the...

- Stretching of a Polymer Below the Î˜ Point. Rosa, A.; Marenduzzo, D.; Maritan, A.; Seno, F. // AIP Conference Proceedings;2003, Vol. 661 Issue 1, p270
The unfolding of a polymer below the Î¸ point when pulled by an external force is studied both in d = 2 on the lattice and in d = 3 off lattice. A ground state analysis of finite length chains shows that the globule unfolds via multiple steps, corresponding to transitions between different...

- AB INITIO DENSITY FUNCTIONAL THEORY INVESTIGATION OF STRUCTURAL AND ELECTRONIC PROPERTIES OF ZnO BUNDLES. FATHALIAN, ALI; MORADIAN, ROSTAM; SANI, SHAHDOKHT SOHRABI // Modern Physics Letters B;12/20/2010, Vol. 24 Issue 31, p2997
By using ab initio density functional theory we investigated the structural and electronic properties of semiconducting (9, 0), zinc oxide zigzag nanotube (ZnOZNT) bundle. The energetic and electronic evolutions of nanotubes in the bundling process are also studied. The effects of inter-tube...

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Presents a study which compared versions of the effective-mass approximation to the exact atomic wave function in predicting the energies of the bound states in a single quantum well. Details on studies of bound states in thin heterojunction quantum wells; Properties of a delta-function...

- Thermodynamics of a magnetic impurity in a small metallic grain. Schlottmann, P. // Journal of Applied Physics;5/15/2003, Vol. 93 Issue 10, p8358
We consider a small metallic sphere with a spin-1/2 impurity at its center. For a contact Kondo exchange and equally spaced s states, the problem is reduced to the Bethe Ansatz solution of the Kondo model in a finite box. The energy spacing is an additional energy scale competing with the Kondo...