We introduce an excited state theory for the optimized
orbital coupled cluster doubles (OO-CCD) and valence
optimized orbital coupled cluster doubles (VOO-CCD) models.
The equations for transition energies are derived using a
similarity transformed Hamiltonian. The effects of orbital
relaxation are discussed. We present results for several
single-reference molecules (H_{2}O,
CH_{2}O, C_{2}H_{4}O,
C_{2}H_{4}, BeO), as well as for molecules
with significant non-dynamical correlation in the ground
state (CH^{+}, BH, A ^{1}A_{1}
CH_{2}), and for rectangular
O_{4}^{+}. We find that: (i) OO-CCD
excitation energies are very close to CCSD excitation
energies; (ii) similarly to the complete active space SCF
(CASSCF) model, the effects of orbital relaxation are very
important for VOO-CCD excited states such that the
excitation energies calculated by VOO-CCD and CASSCF with
orbitals optimized for the ground state are very close to
each other and unsatisfactory; (iii) the VOO-CCD model with
an approximate treatment of orbital relaxation describes
singly (valence and Rydberg) and doubly (valence) excited
states within errors of 0.2-1.0 eV at equilibrium
geometries and along bond-breaking coordinates; (iv) the
above accuracy of VOO-CCD model does not degrade as
molecules or basis sets grow in size; (v) the shapes of
potential energy surfaces around excited states minima are
reproduced well by VOO-CCD model suggesting the use of this
method for excited states geometry optimization.