  This paper presents the first implementation of a coupling between advanced
wave function theories and molecular density functional theory (MDFT). This
method enables the modeling of solvent effect into quantum mechanical (QM)
calculations by incorporating an electrostatic potential generated by solvent
charges into the electronic Hamiltonian. Solvent charges are deduced from the
spatially and angularly dependent solvent particle density. Such density is
obtained through the minimization of the functional associated to the molecular
mechanics (MM) Hamiltonian describing the interaction between the fluid
particles. The introduced QM/MDFT framework belongs to QM/MM family of methods
but its originality lies in the use of MDFT as the MM solver, offering two main
advantages. Firstly, its functional formulation makes it competitive with
respect to sampling-based molecular mechanics. Secondly, it preserves a
molecular-level description lost in macroscopic continuum approaches. Excited
states properties of water and formaldehyde molecules solvated into water have
been computed at the selected configuration interaction (SCI) level. Excitation
energies and dipole moment have been compared with experimental data and
previous theoretical work. A key finding is that using the Hartree-Fock method
to describe the solute allows for predicting the solvent charge around the
ground-state with sufficient precision for the subsequent SCI calculations of
excited-states. This significantly reduces the computational cost of the
described procedure, paving the way for the study of more complex molecules.
