Tight-Binding Formalism for Ionic Fullerides and its Application to Alkali-C60 Polymers

1997 ◽  
Vol 491 ◽  
Author(s):  
Susumu Saito ◽  
Steven G. Louie ◽  
Marvin L. Cohen
Keyword(s):  
Density Wave ◽  
Tight Binding ◽  
Stable State ◽  
Coulomb Repulsion ◽  
Binding Model ◽  
Wave State ◽  
Madelung Energy ◽  
The One ◽  
Consistent Treatment ◽  
Ionic Lattice

ABSTRACTWe present a tight-binding formalism which can properly treat various ionic füllendes. In the Hamiltonian we include the intrafullerene Coulomb repulsion energy and the Madelung energy of the ionic lattice, both of which depend on the possible charge disproportion between fullerenes. This Hamiltonian requires a self-consistent treatment, but it is applicable to much larger systems than first-principles methods. Using this formalism we have studied the electronic structure of the one-dimensional A1C60 polymer. The present generalization of the tight-binding model is found to be important for ionic füllendes and a moderate-amplitude charge-density-wave state is found to be a possible stable state.

AN ADAPTATION OF THE AUGMENTED SPACE APPROACH TO RANDOM MAGNETIC ALLOYS: AN APPLICATION TO Ni1−xFex

1990 ◽  
Vol 04 (04) ◽  
pp. 605-618 ◽  
Author(s):  
ABHIJIT MOOKERJEE ◽  
ARUN K. MISHRA
Keyword(s):  
Tight Binding ◽  
Coulomb Repulsion ◽  
Spin Fluctuations ◽  
Ferromagnetic Alloy ◽  
Binding Model ◽  
Anderson Hamiltonian ◽  
Augmented Space ◽  
Random Magnetic Alloys ◽  
Space Method ◽  
Space Approach

An application of CPA and cluster CPA to Ni rich Ni 1−x Fe x ferromagnetic alloy on the basis of multiband tight binding model is discussed. The augmented space method of Mookerjee1 has been extended to include the case where the potential is generated self-consistently. The tight binding Anderson Hamiltonian incorporates a term to account for the opposite Coulomb repulsion of electrons. The resulting Anderson-Hubbard Hamiltonian is used to consider the spin fluctuations and moment formation, on alloying, of the transition metal Ni with Fe.

Plasmon excitations in doped square-lattice atomic clusters

2017 ◽  
Vol 31 (30) ◽  
pp. 1750233 ◽  
Author(s):  
Yaxin Wang ◽  
Ya-Bin Yu
Keyword(s):  
Tight Binding ◽  
Blue Shift ◽  
Coulomb Repulsion ◽  
Atomic Clusters ◽  
Red Shift ◽  
Square Lattice ◽  
Local Mode ◽  
Two Dimensional ◽  
Binding Model ◽  
Dopant Atoms

Employing the tight-binding model, we theoretically study the properties of the plasmon excitations in doped square-lattice atomic clusters. The results show that the dopant atoms would blur the absorption spectra, and give rise to extra plasmon resonant peaks as reported in the literature; however, our calculated external-field induced oscillating charge density shows that no obvious evidences indicate the so-called local mode of plasmon appearing in two-dimensional-doped atomic clusters, but the dopants may change the symmetry of the charge distribution. Furthermore, we show that the disorder of the energy level due to dopant makes the absorption spectrum has a red- or blue-shift, which depends on the position of impurities; disorder of hopping due to dopant makes a blue- or red-shift, a larger (smaller) hopping gives a blue-shift (red-shift); and a larger (smaller) host-dopant and dopant–dopant intersite coulomb repulsion induces a blue-shift (red-shift).

scholarly journals Conditions for fully gapped topological superconductivity in topological insulator nanowires

2019 ◽  
Vol 6 (5) ◽  
Author(s):  
Fernando de Juan ◽  
Jens H Bardarson ◽  
Roni Ilan
Keyword(s):  
Topological Insulator ◽  
Continuum Model ◽  
Rotational Symmetry ◽  
Tight Binding ◽  
Majorana Fermions ◽  
Tight Binding Model ◽  
Binding Model ◽  
One Dimensional ◽  
Topological Superconductors ◽  
The One

Among the different platforms to engineer Majorana fermions in one-dimensional topological superconductors, topological insulator nanowires remain a promising option. Threading an odd number of flux quanta through these wires induces an odd number of surface channels, which can then be gapped with proximity induced pairing. Because of the flux and depending on energetics, the phase of this surface pairing may or may not wind around the wire in the form of a vortex. Here we show that for wires with discrete rotational symmetry, this vortex is necessary to produce a fully gapped topological superconductor with localized Majorana end states. Without a vortex the proximitized wire remains gapless, and it is only if the symmetry is broken by disorder that a gap develops, which is much smaller than the one obtained with a vortex. These results are explained with the help of a continuum model and validated numerically with a tight binding model, and highlight the benefit of a vortex for reliable use of Majorana fermions in this platform.

Semiconductivity of Protein: The Saxon–Hutner–Luttinger Theorem in Biopolymers

1997 ◽  
Vol 11 (24) ◽  
pp. 2941-2960
Author(s):  
Kazumoto Iguchi
Keyword(s):  
Amino Acid ◽  
Amino Acid Sequence ◽  
Tight Binding ◽  
Tight Binding Model ◽  
Transfer Matrices ◽  
Binding Model ◽  
One Dimensional ◽  
Long Time ◽  
Set Up ◽  
The One

We study semiconductivity of protein with a primary structure, where we use the transfer matrix method of the tight-binding model for electrons in a protein. We first introduce the model and the scheme for obtaining the spectrum. Second, we set up the transfer matrices in order to apply for a protein with an amino acid sequence. Third, we prove the Saxon–Hutner conjecture for the one-dimensional disordered polyatomic chains, and apply it to the protein system. We show that this theorem provides a good foundation for understanding the intriguing semiconductive character of the protein, which was first suggested by Szent–Györgyi a long time ago.

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