MPSGeometry

full name: tenpy.networks.mps.MPSGeometry
parent module: tenpy.networks.mps
type: class

Inheritance Diagram

Methods

`MPSGeometry.__init__`(sites, bc[, ...])
`MPSGeometry.get_site`(i)	Get the i-th site.
`MPSGeometry.shift_Array_unit_cells`(arr, ...)	Shift an Array by an integer multiple of unit cells.
`MPSGeometry.shift_Site_unit_cells`(site, ...)	Shift a site by an integer multiple of unit cells.
`MPSGeometry.shift_charges_unit_cells`(...)	Shift charges by an integer multiple of unit cells.
`MPSGeometry.test_sanity`()

Class Attributes and Properties

`MPSGeometry.L`	Number of physical sites; for an iMPS the len of the MPS unit cell.
`MPSGeometry.N_sites_per_hor_spacing`	Number of sites per horizontal lattice spacing.
`MPSGeometry.dim`	List of local physical dimensions.
`MPSGeometry.finite`	Distinguish MPS vs iMPS.
`MPSGeometry.nontrivial_bonds`	Slice of the non-trivial bond indices, depending on `self.bc`.

class tenpy.networks.mps.MPSGeometry(sites, bc, unit_cell_width=None)[source]

Bases: object

Base class providing methods regarding the 1D geometry of MPS-like tensornetworks.

Parameters:

sites (list of Site) – Defines the local Hilbert space for each site.
bc ('finite' | 'segment' | 'infinite') – Boundary conditions as described in the table of the module doc-string.
unit_cell_width (int) – See mps_unit_cell_width.

chinfo

The nature of the charge.

Type:: ChargeInfo

sites

Defines the local Hilbert space for each site.

Type:: list of Site

bc

Boundary conditions as described in the table of the module doc-string.

Type:: 'finite' | 'segment' | 'infinite'

unit_cell_width

The width (i.e. length along the first dimension) of an MPS unit cell, in units of the lattice spacing. It is given by mps_unit_cell_width. For a Chain, this is just the length of the chain. Is used for Dipole Conservation or MPS.correlation_length2().

Type:: int

property L: Number of physical sites; for an iMPS the len of the MPS unit cell.

property dim: List of local physical dimensions.

property finite

Distinguish MPS vs iMPS.

True for an MPS (bc='finite', 'segment'), False for an iMPS (bc='infinite').

property nontrivial_bonds: Slice of the non-trivial bond indices, depending on self.bc.

property N_sites_per_hor_spacing

Number of sites per horizontal lattice spacing.

This is the number of MPS sites one has to traverse to travel one lattice spacing in the first dimension, such that self.unit_cell_width * N_sites_per_hor_spacing == self.L.

shift_charges_unit_cells(charges, num_unit_cells)[source]

Shift charges by an integer multiple of unit cells.

See the notes on Dipole Conservation.

A unit cell has length L and a shift by one unit cell is purely horizontal and shifts by unit_cell_width lattice spacings.

Essentially, this is a convenience wrapper around \(tenpy.linalg.charges.ChargeInfo.shift_charges_horizontal\).

Parameters:

charges (2D ndarray of dtype QTYPE) – The charges to shift.
num_unit_cells (int) – The number of unit cells.

Returns:

The shifted charges.

Return type:

2D ndarray of dtype QTYPE

shift_Site_unit_cells(site, num_unit_cells)[source]

Shift a site by an integer multiple of unit cells.

See the notes on Dipole Conservation.

A unit cell has length L and a shift by one unit cell is purely horizontal and shifts by unit_cell_width lattice spacings.

Parameters:

site (Site) – The site to shift.
num_unit_cells (int) – The number of unit cells.

Returns:

A new site with shifted charges, or the unmodified input site if the shift is trivial.

Return type:

Site

shift_Array_unit_cells(arr, num_unit_cells, inplace: bool = False)[source]

Shift an Array by an integer multiple of unit cells.

See the notes on Dipole Conservation.

A unit cell has length L and a shift by one unit cell is purely horizontal and shifts by unit_cell_width lattice spacings.

Parameters:

arr (Array) – The site to shift.
num_unit_cells (int) – The number of unit cells.
inplace (bool) – If the array (its legs, qtotal) can be modified in-place. Otherwise (default) we make a shallow copy.

Returns:

The shifted array.

Return type:

Array

get_site(i)[source]

Get the i-th site.

This is self.sites[i] if i is in the unit cell and takes care of shifting the charges otherwise.