  A new perturbative approach to canonical equation-of-motion coupled-cluster
theory is presented using coupled-cluster perturbation theory. A second-order
M{\o}ller-Plesset partitioning of the Hamiltonian is used to obtain the well
known equation-of-motion many-body perturbation theory (EOM-MBPT(2)) equations
and two new equation-of-motion methods based on the linear coupled-cluster
doubles (EOM-LCCD) and linear coupled-cluster singles and doubles (EOM-LCCSD)
wavefunctions. This is achieved by performing a short-circuiting procedure on
the MBPT(2) similarity transformed Hamiltonian. These new methods are
benchmarked against very accurate theoretical and experimental spectra from 25
small organic molecules. It is found that the proposed methods have excellent
agreement with canonical EOM-CCSD state for state orderings and relative
excited state energies as well as acceptable quantitative agreement for
absolute excitation energies compared with the best estimate theory and
experimental spectra.
