  We present the first application to real molecular systems of the recently
proposed linear-response theory for the density-based basis-set correction
method [J. Chem. Phys. 158, 234107 (2023)]. We apply this approach to
accelerate the basis-set convergence of excitation energies in the
equation-of-motion coupled-cluster singles doubles (EOM-CCSD) method. We use an
approximate linear-response framework which neglects the second-order
derivative of the basis-set correction density functional and consists in
simply adding to the usual Hamiltonian the one-electron potential generated by
the first-order derivative of the functional. This additional basis-set
correction potential is evaluated at the Hartree-Fock density, leading to a
very computationally cheap basis-set correction. We tested this approach over a
set of about 30 excitation energies computed for five small molecular systems
and found that the excitation energies from the ground state to Rydberg states
are the main source of basis-set error. These excitation energies
systematically increase when the size of the basis set is increased, suggesting
a biased description in favour of the excited state. Despite the simplicity of
the present approach, the results obtained with the basis-set corrected
EOM-CCSD method are encouraging as they yield to a mean absolute deviation of
0.02 eV for the aug-cc-pVTZ basis set, while it is of 0.04 eV using the
standard EOM-CCSD method. This might open the path to an alternative to
explicitly correlated approaches to accelerate the basis-set convergence of
excitation energies.
