XXZ chains: finite states and thermodynamic excitations¶
The XXZ anisotropy changes both the physics and the root families used by the solver. Choose the boundary condition and calculation before selecting a tool.
| What to calculate | Program | Coverage and guide |
|---|---|---|
| Periodic ground states and sector minima | bethe-xxz-pbc |
Periodic XXZ: Delta>=0, and -1<Delta<0 on even rings |
| Free-end ground states and sector minima | bethe-xxz-obc |
Open XXZ: Delta>-1, including massive boundary roots |
| Selected real-root excitation scans | Either finite-chain tool | The respective guide restricts these scans to 0<=Delta<=1 |
| Zero-field bulk energy, spinons and two-spinon continuum edges | bethe-xxz-dispersion |
Thermodynamic dispersion: gapless and massive regimes, Delta>-1 |
| Massive transverse two-spinon intensity | bethe-xxz-structure-factor-thermo |
Spectral density: zero field, Delta>1, separate sheets and physical weights |
| Quantum-group open chain with imaginary end fields | bethe-xxz-qg-obc |
Non-Hermitian XXZ: regular roots and the distinct free-point/Jordan-block calculation |
MPS and iMPS comparisons¶
The spinon tutorial explains the spin normalization, physical momentum, two-site-cell folding and continuum boundaries. An envelope locates allowed energies; it is not an operator-dependent spectral intensity. The non-Hermitian tutorial instead concerns different boundary fields and spectral/Jordan structure.
Numerical methods and specialized APIs¶
These pages explain additional methods or restricted constructions; their existence does not extend the finite-chain CLI domains in the table above.
- Massive open-chain roots and negative anisotropy explain branch choices and limits.
- Negative odd-ring continuation records the restricted continuation problem and unresolved coverage outside the public frontend.
- Open-chain Q-system and targeted two-strings underpin complex-root biquadratic/TL calculations.
- Spin-helix states, phantom roots, phantom consistency checks and phantom wavefunctions concern special eigenstates.
- Coordinate wavefunctions, polynomial equations, Wronskian constraints and regularity discuss how candidate roots are tested.
For the physical spin-1 chains represented by some of these auxiliary equations, continue with the biquadratic family guide.