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Condensed-Matter Models

Condensed-matter model cards summarize standard lattice and band models used to teach hopping, band formation, Dirac points, topology, and superconducting mean-field phases. They are lookup cards: Quantum Matter Reference and Data routes a requested model to its material-facing convention and provenance record and to the page that owns its physics; these cards retain compact model identification and assumptions.

ModelMain lessonCore formalism
Tight-Binding ChainNearest-neighbor hopping produces a cosine bandBloch Theorem
Graphene Dirac ModelHoneycomb sublattices give valley Dirac conesBloch Theorem
SSH ModelDimerized hopping realizes a one-dimensional winding invariantBerry Curvature
Kitaev ChainA one-dimensional p-wave superconductor supports Majorana end modes in its topological phaseTopological Invariants

For any condensed-matter model, specify:

  • lattice geometry and boundary conditions;
  • orbitals or sublattices per unit cell;
  • whether spin, interactions, disorder, and magnetic fields are included;
  • hopping, onsite, pairing, or mass-term conventions;
  • Brillouin-zone convention and lattice spacing;
  • symmetry assumptions used for any topological statement.
  • Treating a band Hamiltonian as a complete material model.
  • Forgetting spin, valley, sublattice, orbital, or boundary-condition degeneracies.
  • Comparing topological phases without checking which symmetries are preserved.
  • Applying a low-energy Dirac expansion far from the expansion point.
  • Treating edge states as automatic without specifying termination and gap assumptions.
  • N. W. Ashcroft and N. D. Mermin, Solid State Physics, Holt, Rinehart and Winston, 1976.
  • S. H. Simon, The Oxford Solid State Basics, Oxford University Press, 2013.
  • B. A. Bernevig and T. L. Hughes, Topological Insulators and Topological Superconductors, Princeton University Press, 2013.
  • J. K. Asbóth, L. Oroszlány, and A. Pályi, A Short Course on Topological Insulators, Springer, 2016.