TwoSiteMixer¶

Inheritance Diagram

Methods

`TwoSiteMixer.__init__`(args, *kwargs)
`TwoSiteMixer.perturb_svd`(engine, theta, i0, ...)	Preform a subspace expansion of a single-site wave function on one side.
`TwoSiteMixer.update_amplitude`(sweeps)	Update the amplitude, possibly disable the mixer.

Class Attributes and Properties

how many sites the theta in perturb_svd should have

class tenpy.algorithms.dmrg.TwoSiteMixer(*args, **kwargs)[source]¶

perturb_svd(engine, theta, i0, move_right)[source]¶

Preform a subspace expansion of a single-site wave function on one side.

Parameters

engine (DMRGEngine) – The DMRG engine calling the mixer.
theta (Array) – The optimized wave function, prepared for svd, with labels '(vL.p0)', 'vR' for right move, or 'vL', '(p0.vR)' for left move.
i0 (int) – The site index where theta lives.
move_right (bool) – Whether we move to the right (True) or left (False).

Returns

U, VH (Array) – Left and right part of the subspace-expanded svd. Always such that the contraction U.S.VH resembles the original theta up to truncation error. U has labels '(vL.p0)', 'vR' (right move) or 'vL', 'vR' (left move). V has labels 'vL', 'vR' (right move) or '(vL.p0)', 'vR' (left move). For a right move, only U is canonical; for a left-move only VH is canonical.
S (1D ndarray) – (Perturbed) singular values on the new bond.
err (TruncationError) – The truncation error introduced.
S_approx (ndarray) – Same as S.

update_amplitude(sweeps)[source]¶

Update the amplitude, possibly disable the mixer.

Parameters: sweeps (int) – The number of performed sweeps, to check if we need to disable the mixer.
Returns: mixer – Returns self if we should continue mixing, or None, if the mixer should be disabled.
Return type: Mixer | None