  We present a combination of three-dimensional reference interaction site
model self-consistent field (3D-RISM-SCF) theory and the variational quantum
eigensolver (VQE) to consider the solvent distribution effects within the
framework of quantum-classical hybrid computing. The present method,
3D-RISM-VQE, does not include any statistical errors from the solvent
configuration sampling owing to the analytical treatment of the statistical
solvent distribution. We apply 3D-RISM-VQE to compute the spatial distribution
functions of solvent water around a water molecule, the potential and Helmholtz
energy curves of NaCl, and to conduct Helmholtz energy component analysis of
H$_2$O and NH$_4^+$. Moreover, we utilize 3D-RISM-VQE to analyze the extent to
which solvent effects alter the efficiency of quantum calculations compared
with calculations in the gas phase using the $L^1$-norms of molecular
electronic Hamiltonians. Our results demonstrate that the efficiency of quantum
chemical calculations on a quantum computer in solution is virtually the same
as in the gas phase.
