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openfermion.utils.Grid

A multi-dimension grid of points with an assigned length scale.

Used in the notebooks

Used in the tutorials

This grid acts as a helper class for parallelpiped super cells. It tracks a mapping from indices to grid points and stores the associated reciprocal lattice with respect to the original real-space lattice. This enables calculations with non-trivial unit cells.

Methods

all_points_indices

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Returns: iterable[tuple[int]]: The index-coordinate tuple of each point in the grid.

grid_indices

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This function is the inverse of orbital_id.

Args
qubit_id (int): The tensor factor to map to grid indices. spinless (bool): Whether to use the spinless model or not.

Returns
grid_indices (numpy.ndarray[int]): The location of the qubit on the grid.

index_to_momentum_ints

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Args: index (tuple): d-dimensional tuple specifying index in the grid Returns: Integer momentum vector

momentum_ints_to_index

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Args: momentum_ints (tuple): d-dimensional tuple momentum integers Returns: d-dimensional tuples of indices

momentum_ints_to_value

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Args: momentum_ints (tuple): d-dimensional tuple momentum integers periodic (bool): Alias the momentum Returns: ndarray containing the momentum vector.

momentum_vector

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Given grid point coordinate, return momentum vector with dimensions.

Args
momentum_indices (list): integers giving momentum indices. Allowed values are ints in [0, grid_length). periodic (bool): Wrap the momentum indices according to periodicity
Returns momentum_vector: A numpy array giving the momentum vector with dimensions.

orbital_id

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Return the tensor factor of a orbital with given coordinates and spin.

Args
grid_coordinates List or tuple of ints giving coordinates of grid element. Acceptable to provide an int(instead of tuple or list) for 1D case. spin (bool): 0 means spin down and 1 means spin up. If None, assume spinless model.

Returns
tensor_factor (int): tensor factor associated with provided orbital label.

position_vector

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Given grid point coordinate, return position vector with dimensions.

Args
position_indices (int|iterable[int]): List or tuple of integers giving grid point coordinate. Allowed values are ints in [0, grid_length).

Returns
position_vector (numpy.ndarray[float])

volume_scale

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Returns: float: The volume of a length-scale hypercube within the grid.

__eq__

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Return self==value.

__ne__

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Return self!=value.