ffsim.singles_excitations_restricted

ffsim.singles_excitations_restricted(t1)

Restricted singles excitations operator.

The restricted singles excitations operator is

\[T_1 = \sum_{ia} t_{ia} (a^\dagger_{a\alpha} a_{i\alpha} + a^\dagger_{a\beta} a_{i\beta})\]

where \(i\) runs over occupied orbitals, \(a\) runs over virtual orbitals, and \(t_{ia}\) are the singles amplitudes.

Parameters:

t1 (ndarray) – The singles amplitudes tensor of shape (nocc, nvrt), where nocc is the number of occupied orbitals and nvrt is the number of virtual orbitals.

Return type:

FermionOperator

Returns:

The singles excitations operator.