BO /contentBottomTemplate
Tight binding models for high temperature superconductors
This page lists a set of tightbinding models that are suitable to describe high temperature superconductors
Some of the models have been compiled from the literature for comparison, others are calculated using first principles calculations or adjusted to match experimental measured quantities.
For each model, the hopping parameters are given in a comma separated file (csv), and basic plots of the band structure and Fermi surface are provided for comparison.
The tightbinding file contains lines with the following format:
r_{x}, r_{y}, r_{z}, a, b, Re(t), Im(t)
Here r_{i} is the ith component of the real space vector that describes the hopping process, a and b are integer numbers labeling the orbitals and the last two entries are the real and imaginary part of the hopping (usually given in eV).
The corresponding Bloch Hamiltonian (in orbital representation) can be obtained by a Fourier transform and summation over all lines to yield the matrix H_{ab}.

Models
Simple 1 band model with nearest neighbor and next nearest neighbor hopping parameter; note the energy unit is fixed to the nearest neighbor hopping t=1.
Around half filling, this model describes the lowenergy electronic structure of Cuprate materials and has been used widely in the literature. Some of my own investigations include

A. T. Rømer, A. Kreisel, I. Eremin, M. A. Malakhov, T. A. Maier, P. J. Hirschfeld, B. M. Andersen
Phys. Rev. B
92, 104505 (2015)
Pairing symmetry of the oneband Hubbard model in the paramagnetic weakcoupling limit: a numerical RPA study
A. Kreisel, A. T. Rømer, P. J. Hirschfeld, B. M. Andersen
J. Supercond. Nov. Magn.
30, 85 (2017)
Superconducting phase diagram of the paramagnetic oneband Hubbard model Publishers version
Fermi surface at filling of 0.45.

Gap symmetry function for leading superconducting instability using spinfluctuation theory. (Rømer, et al., Phys. Rev. B 92, 104505 (2015))

Noninteracting (green) and RPA susceptibility.

Density of states.

Band structure along high symmetry directions.
