LanczosGroundState¶
full name: tenpy.linalg.krylov_based.LanczosGroundState
parent module:
tenpy.linalg.krylov_based
type: class
Inheritance Diagram

Methods
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Find the ground state of H. |
- class tenpy.linalg.krylov_based.LanczosGroundState(H, psi0, options, orthogonal_to=[])[source]¶
Bases:
KrylovBased
Lanczos algorithm to find the ground state.
Assumes that H is hermitian.
Deprecated since version 0.6.0: Renamed attribute params to
options
.Deprecated since version 0.6.0: Going to remove the orthogonal_to argument. Instead, replace H with
OrthogonalNpcLinearOperator(H, orthogonal_to)
using theOrthogonalNpcLinearOperator
.Options
- config LanczosGroundState¶
option summary cutoff (from KrylovBased) in KrylovBased
Cutoff to abort if the norm of the new krylov vecotr is too small. [...]
E_shift (from KrylovBased) in KrylovBased
Shift the energy (=eigenvalues) by that amount *during* the Lanczos run by [...]
Stop if energy difference per step < `E_tol`
min_gap (from KrylovBased) in KrylovBased
Lower cutoff for the gap estimate used in the P_tol criterion.
The maximum number of `psi` to keep in memory during the first iteration. [...]
N_max (from KrylovBased) in KrylovBased
Maximum number of steps to perform.
N_min (from KrylovBased) in KrylovBased
Minimum number of steps to perform.
P_tol (from KrylovBased) in KrylovBased
Tolerance for the error estimate from the Ritz Residual, [...]
For poorly conditioned matrices, one can quickly loose orthogonality of the [...]
- option E_tol: float¶
Stop if energy difference per step < E_tol
- option N_cache: int¶
The maximum number of psi to keep in memory during the first iteration. By default, we keep all states (up to N_max). Set this to a number >= 2 if you are short on memory. The penalty is that one needs another Lanczos iteration to determine the ground state in the end, i.e., runtime is large.
- option reortho: bool¶
For poorly conditioned matrices, one can quickly loose orthogonality of the generated Krylov basis. If reortho is True, we re-orthogonalize against all the vectors kept in cache to avoid that problem.