# Developers:FutureTutorials:ED Lattice models

From ALPS

# Quantum Magnetism

**Spin S Heisenberg chains & ladders**

**t-J chains & t-J Ladders**

**Continuous Symmetry Breaking in 2D: Tower of States**

Physical examples (or a subset thereof):

- S=1/2 Square lattice AFM (collinear Néel order)
- S=1/2 Triangular lattice (noncollinear 120 degree order)
- S=1 bilinear-biquadratic square lattice (Ferroquadrupolar order)
- hardcore bosons (superfluid)

Calculate low lying energy spectrum with Lanczos or fulldiag extract total S (if applicable) of each eigenstate. Simple for fulldiag, more involved based on partial Lanczos spectra

Requirements:

- Flexible cluster interface, Lattice library redesign
- Add a flux through the system
- Spectral functions

**Fidelity**

Calculate the phase diagram of say the 1D transverse field Ising model using fidelity

Requirements:

- calculate overlaps of wave functions (in the same sector, when calculating sector based data)
- calculate entanglement & entanglement spectra