ZeroSiteH

full name: tenpy.algorithms.mps_common.ZeroSiteH
parent module: tenpy.algorithms.mps_common
type: class

Inheritance Diagram

Methods

`ZeroSiteH.__init__`(env, i0)
`ZeroSiteH.adjoint`()	Return the hermitian conjugate of self.
`ZeroSiteH.combine_theta`(theta)	Combine the legs of theta, such that it fits to how we combined the legs of self.
`ZeroSiteH.from_LP_RP`(LP, RP[, i0])
`ZeroSiteH.matvec`(theta)	Apply the effective Hamiltonian to theta.
`ZeroSiteH.to_matrix`()	Contract self to a matrix.
`ZeroSiteH.update_LP`(env, i[, U])	Equivalent to `env.get_LP(i, store=True)`; optimized for combine.
`ZeroSiteH.update_RP`(env, i[, VH])	Equivalent to `env.get_RP(i, store=True)`; optimized for combine.

Class Attributes and Properties

`ZeroSiteH.acts_on`
`ZeroSiteH.length`

class tenpy.algorithms.mps_common.ZeroSiteH(env, i0)[source]

Bases: EffectiveH

Class defining the zero-site effective Hamiltonian for Lanczos.

The effective zero-site Hamiltonian looks like this:

|        .---    ---.
|        |          |
|       LP----------RP
|        |          |
|        .---    ---.

Note that this class has less functionality than the OneSiteH and TwoSiteH.

Parameters:

env (MPOEnvironment) – Environment for contraction <psi|H|psi>.
i0 (int) – Site index such that LP is everything strictly left of i0.

length

Number of (MPS) sites the effective hamiltonian covers.

Type:: int

acts_on

Labels of the state on which self acts. NB: class attribute. Overwritten by normal attribute, if combine.

Type:: list of str

LHeff, RHeff

Only set if combine, and only one of them depending on move_right. If move_right was True, LHeff is set with labels '(vR*.p0)', 'wR', '(vR.p0*)' for bra, MPO, ket; otherwise RHeff is set with labels '(p0*.vL)', 'wL', '(p0, vL*)'

Type:: Array

LP, W0, RP

Tensors making up the network of self.

Type:: Array

matvec(theta)[source]

Apply the effective Hamiltonian to theta.

Parameters:: theta (Array) – Labels: vL, vR.
Returns:: Product of theta and the effective Hamiltonian.
Return type:: theta Array

to_matrix()[source]: Contract self to a matrix.

adjoint()[source]: Return the hermitian conjugate of self.

combine_theta(theta)[source]

Combine the legs of theta, such that it fits to how we combined the legs of self.

Parameters:: theta (Array) – Wave function to apply the effective Hamiltonian to, with uncombined legs.
Returns:: theta – Wave function with labels as given by self.acts_on.
Return type:: Array

update_LP(env, i, U=None)[source]

Equivalent to env.get_LP(i, store=True); optimized for combine.

Parameters:

env (MPOEnvironment) – The same environment as given during class initialization.
i (int) – We update the part left of site i. Can optimize if i == i0 and combine is True.
U (None | Array) – The tensor on the left-most site self acts on, with combined legs after SVD. Only used if trying to optimize.

update_RP(env, i, VH=None)[source]

Equivalent to env.get_RP(i, store=True); optimized for combine.

Parameters:

env (MPOEnvironment) – The same environment as given during class initialization.
i (int) – We update the part right of site i. Can optimize if i == i0 + 2 - length and combine is True.
U (None | Array) – The tensor on the right-most site self acts on, with combined legs after SVD. Only used if trying to optimize.