ExcitationInitialState

full name: tenpy.simulations.ground_state_search.ExcitationInitialState
parent module: tenpy.simulations.ground_state_search
type: class

Inheritance Diagram

Methods

`ExcitationInitialState.__init__`(sim, options)
`ExcitationInitialState.check_filling`(p_state)	Ensure that the filling of the product state matches check_filling parameter.
`ExcitationInitialState.check_total_charge`(psi)	Assert that the given state has the expected charge.
`ExcitationInitialState.desired_bond_dimension`([chi])	Initialize a trivial charge MPS with desired bond dimension.
`ExcitationInitialState.fill_where`()	Allow to specify a condition where sites should be filled.
`ExcitationInitialState.fill_where__get_variables`()	Define the variables which can be used in the condition of `fill_where()`.
`ExcitationInitialState.from_file`()	Load the initial state from an existing file.
`ExcitationInitialState.from_orthogonal`()
`ExcitationInitialState.lat_product_state`([...])	Initialize from a lattice product state.
`ExcitationInitialState.mps_product_state`([...])	Initialize from a product state.
`ExcitationInitialState.mps_state_in_charge_sector`([...])	Initialize a state on a lattice already in a desired charge sector.
`ExcitationInitialState.randomized`()	Initialize a state with another method and then apply a RandomUnitaryEvolution.
`ExcitationInitialState.run`()	Build an initial state from a specified method.

Class Attributes and Properties

ExcitationInitialState.logger

class attribute.

class tenpy.simulations.ground_state_search.ExcitationInitialState(sim, options)[source]

Bases: InitialStateBuilder

InitialStateBuilder for OrthogonalExcitations.

Parameters:

sim (OrthogonalExcitations) – Simulation class for which an initial state needs to be defined.
options (dict) – Parameter dictionary as described below.

Options

config ExcitationInitialState

option	summary
allow_incommensurate (from InitialStateBuilder) in InitialStateBuilder.lat_product_state	See :meth:`MPS.from_lat_product_state`.
charge_sector (from InitialStateBuilder) in InitialStateBuilder.mps_state_in_charge_sector	The `charge_sector` passed on to :meth:`MPS.project_onto_charge_sector`. [...]
check_filling (from InitialStateBuilder) in InitialStateBuilder.check_filling	The desired filling as float ``p/q``, or by a tuple ``(p, q)``. [...]
chi (from InitialStateBuilder) in InitialStateBuilder.desired_bond_dimension	The desired bond dimension passed on to :meth:`MPS.from_desired_bond_dimension`.
data_key (from InitialStateBuilder) in InitialStateBuilder.from_file	Key within the file to be used for loading the data. [...]
filename (from InitialStateBuilder) in InitialStateBuilder.from_file	The filename from which to load the state
fill_where (from InitialStateBuilder) in InitialStateBuilder.fill_where	A string specifying the condition where to fill sites. [...]
full_empty (from InitialStateBuilder) in InitialStateBuilder.check_filling	Definition of which local states are "full" and "empty". [...]
method (from InitialStateBuilder) in InitialStateBuilder	Selects the category of the initial state, and in particular the [...]
product_state (from InitialStateBuilder) in InitialStateBuilder.lat_product_state	The `p_state` passed on to :meth:`MPS.from_lat_product_state`.
randomize_canonicalize (from InitialStateBuilder) in InitialStateBuilder.randomized	Whether to call :meth:`MPS.canonical_form` before returning the state.
randomize_close_1	Whether to randomize/perturb with unitaries close to the identity.
randomize_params	Parameters for the random unitary evolution used to perturb the state a lit [...]
randomized_from_method (from InitialStateBuilder) in InitialStateBuilder.randomized	Selects another method to initialize the starting state to be randomized, [...]
use_highest_excitation	If True, start from the last state in :attr:`orthogonal_to` and perturb it [...]

option randomize_params: dict-like: Parameters for the random unitary evolution used to perturb the state a little bit in perturb().

option randomize_close_1: bool: Whether to randomize/perturb with unitaries close to the identity.

option use_highest_excitation: bool: If True, start from the last state in orthogonal_to and perturb it. If False, use the ground state (=the first entry of orthogonal_to and perturb that one a little bit.

sim

Simulation class for which to initial a state to be used as excitation initial state.

Type:: OrthogonalExcitations

check_filling(p_state)[source]

Ensure that the filling of the product state matches check_filling parameter.

Options

option InitialStateBuilder.check_filling: None | (int, int) or float: The desired filling as float p/q, or by a tuple (p, q). None (default) disables the check.

option InitialStateBuilder.full_empty: (str, str): Definition of which local states are “full” and “empty”. For example you can use full_empty=('up', 'down') if you have spin sites.

check_total_charge(psi)[source]

Assert that the given state has the expected charge.

Parameters:

psi (MPS) – The final, generated state.
cfg (..) –

check_total_chargetuple of int
Check that the MPS.get_total_charge() returns these values.

desired_bond_dimension(chi=None)[source]

Initialize a trivial charge MPS with desired bond dimension.

See MPS.from_desired_bond_dimension() for details.

Options

option InitialStateBuilder.chi: int: The desired bond dimension passed on to MPS.from_desired_bond_dimension().

fill_where()[source]

Allow to specify a condition where sites should be filled.

Warning

The fill_where string is parsed with the python function eval; this is unsafe if the variable comes from an untrusted source (e.g. the internet).

Options

option InitialStateBuilder.fill_where: str: A string specifying the condition where to fill sites. See examples in fill_where().

option InitialStateBuilder.full_empty: (str, str): Definition of which local states are “full” and “empty”. For example you can use full_empty=('up', 'down') if you have spin sites.

Examples

Possible variables for conditions are specified in fill_where__get_variables(), for example x_ind, y_ind, u_ind.

You can do arbitrary logical expressions. Example conditions: - "x_ind == 0" - "AND(x_ind == 0, y_ind == 0)" - "AND(x_ind == 0, IN(y_ind, [0, 2])" - "WITHIN(x_ind, 0.25*Lx, 0.75*Lx )" # 0.25*Lx <= x <= 0.75&Lx

fill_where__get_variables()[source]

Define the variables which can be used in the condition of fill_where().

Here, the following variables get defined.

x_ind, y_ind, u_indint: Lattice indices of the
epsfloat: Cutoff 1.e-12 that can get used when it is necessary to compare floats
np :: Numpy module, allowing to use any function from numpy.
AND, OR, XOR, NOT, ANY, ALL, CLOSE, EQUAL, IN, WITHIN: Function aliases to allow logical combinations. Use for example as AND(x_ind == 0, IN(y_ind, [0, 2, 5])).

from_file()[source]

Load the initial state from an existing file.

Options

option InitialStateBuilder.filename: str: The filename from which to load the state

option InitialStateBuilder.data_key: str: Key within the file to be used for loading the data. Can be recursive (separated by ‘/’), see tenpy.tools.misc.get_recursive().

lat_product_state(p_state=None)[source]

Initialize from a lattice product state.

See MPS.from_lat_product_state() for details.

Options

option InitialStateBuilder.product_state: array of str: The p_state passed on to MPS.from_lat_product_state().

option InitialStateBuilder.allow_incommensurate: bool: See MPS.from_lat_product_state().

logger = <Logger tenpy.networks.mps.InitialStateBuilder (WARNING)>

class attribute.

Type:: logger
Type:: An instance of a logger; see Logging and terminal output. NB

mps_product_state(p_state=None)[source]

Initialize from a product state.

See MPS.from_product_state() for details.

Options

option InitialStateBuilder.product_state: list of str: The p_state passed on to MPS.from_product_state().

mps_state_in_charge_sector(charge_sector=None, p_state=None)[source]

Initialize a state on a lattice already in a desired charge sector.

See MPS.project_onto_charge_sector() for details.

Options

option InitialStateBuilder.charge_sector: tuple of int: The charge_sector passed on to MPS.project_onto_charge_sector(). Depending on the number of sites in a lattice, only specific charge sectors can be reached.

option InitialStateBuilder.product_state: list | np.ndarray: Optional. A product_state as in mps_product_state().

randomized()[source]

Initialize a state with another method and then apply a RandomUnitaryEvolution.

Options

option InitialStateBuilder.randomized_from_method: str: Selects another method to initialize the starting state to be randomized, e.g., 'lat_product_state' for lat_product_state().

option InitialStateBuilder.randomize_params: dict-like: Parameters given to the RandomUnitaryEvolution. In particular, you might want to set the N_steps and trunc_params[‘chi_max’]. The default is {'N_steps': 10, 'trunc_params': {'chi_max': max(100, max(psi.chi))}}.

option InitialStateBuilder.randomize_canonicalize: bool: Whether to call MPS.canonical_form() before returning the state.

run()[source]

Build an initial state from a specified method.

Reads out the option InitialStateBuilder.method to choose a method of the class which generates the state.

Returns:: psi – The generated MPS.
Return type:: MPS