SparseOccupationOperators

class fireopal.types.SparseOccupationOperators(operators, coefficients)

A dataclass representing sparse occupation operators.

This class handles observables by accepting a list of terms, where each term is itself a list of (spin, site) tuples. A 1-point observable is represented as a list of length 1, while multi-point observables are lists of length > 1.

Parameters

• operators (list [ list [ tuple [ str , int ] ] ]) – A list of terms making up the operator. Each term is a list of tuples. 1-point observable example: [[(“Nup”, 3)]] Multi-point observable example: [[(“Ndn”, 7), (“Nup”, 9), (“Nup”, 4)]]
• coefficients (list [ float ]) – A list of coefficients corresponding to each operator term in operators. Must be the exact same length as operators.

Raises

• ValueError – If the lengths of operators and coefficients do not match, if an operator tuple does not have exactly 2 elements, or if the spin is not “Nup” or “Ndn”.
• TypeError – If the types within the lists are incorrect (e.g., coefficient is not a number, spin is not a string, or site is not an integer).

Examples

>>> # Case 1: 1-point observables (lists of length 1)
>>> operator_1 = SparseOccupationOperators(
...     operators=[[("Nup", 3)], [("Ndn", 7)]],
...     coefficients=[+1/4, -4/5]
... )

>>> # Case 2: Mixed multi-point and 1-point observables
>>> operator_2 = SparseOccupationOperators(
...     operators=[[("Nup", 3)], [("Ndn", 7), ("Nup", 9), ("Nup", 4)]],
...     coefficients=[+1.0, -1.0]
... )

Methods

Attributes