The amplitudes t α , t n , and t α ñ can be solved by projection (Eq. 36). This requires the evaluation of the similaritytransformed Hamiltonian operator ĤPF = e -T ĤPF e T , where ĤPF is expressed in Eq. 13 and is usually rotated to the coherent state basis (see Sec. 3.2.1). This leads to the ground state coupled cluster energy E CC 0 as a solution to the following set of equations,