ffsim.ccsd_generator_restricted¶

ffsim.ccsd_generator_restricted(t1, t2)[source]¶

Restricted coupled cluster, singles and doubles (CCSD) generator.

The restricted CCSD generator is

\[T = T_1 + T_2\]

where \(T_1\) is the restricted singles excitations operator (see singles_excitations_restricted()) and \(T_2\) is the restricted doubles excitations operator (see doubles_excitations_restricted()).

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.
t2 (ndarray) – The doubles amplitudes tensor of shape (nocc, nocc, nvrt, nvrt), where nocc is the number of occupied orbitals and nvrt is the number of virtual orbitals.

Return type:

FermionOperator

Returns:

The CCSD generator.