Multiconfigurational self-consistent reaction field theory for nonequilibrium solvation

Abstract

We present multiconfigurational self-consistent reaction field theory and implementation for solvent effects on a solute molecular system that is not in equilibrium with the outer solvent. The approach incorporates two different polarization vectors for studying the influence of the solvent. The solute, an atom, a molecule or a supermolecule, is assumed to be surrounded by a linear, homogeneous medium described by two polarization vector fields, the optical polarization vector and the inertial polarization vector fields. The optical polarization vector is always in equilibrium with the actual electronic structure whereas the inertial polarization vector is not necessarily in equilibrium with the actual electronic structure. The electronic structure of the compound is described by a correlated electronic wave function—a multiconfigurational self-consistent field (MCSCF) wave function. This wave function is fully optimized with respect to all variational parameters in the presence of the surrounding polarizable dielectric medium having two distinct polarization vectors. We develop from a compact and simple expression a direct and second-order convergent optimization procedure for the solvent states influenced by the two types of polarization vectors. The general treatment of the correlation problem through the use of complete and restricted active space methodologies makes the present multiconfigurational self-consistent reaction field approach general in that it can handle any type of state, open-shell, excited, and transition states. We demonstrate the theory by computing solvatochromatic shifts in optical/UV spectra of some small molecules and electron ionization and electron detachment energies of the benzene molecule. It is shown that the dependency of the solvent induced affinity in benzene is nonmonotonic with respect the optical dielectric constant if inertial polarization effects also are accounted for.

Singlet Sigma: The “Other” Singlet Oxygen in Solution

“…In an attempt to better understand the effect of solvent on singlet oxygen spectral shifts, we employed ab initio computational methods (35,36) to characterize complexes between a given solvent molecule, M, and oxygen (33). Specifically, we calculated the energies of an M-02(a1Ag) complex that is in equilibrium with its surrounding outer solvent and an M-O2(X3Zg-) complex that is not in equilibrium with the outer solvent (i.e.…”

Continuous medium theory for nonequilibrium solvation: III. Solvation shift by monopole approximation and multipole expansion in spherical cavity

“…25,26,41 However, in general, a realistic charge distribution of a neutral or ionic molecular system in the cavity, even if the cavity is approximated to be spherical, can be simply described by neither monopole nor point dipole. The multipole expansion approach, 5,42,43 in such cases, should be adopted.…”

Reaction field spectral shifts with semiempirical molecular orbital theory

“…In particular, Hartree᎐Fock, MCSCF, and CI level ab initio treatments have w been considered. Although Mikkelson et al 84, x 85 considered only spheroidal solutes for which the solution polarization was obtained in analytiw x cal form, Aguilar and Olivares del Valle 83 treated more generally shaped solutes for which the solution polarization was obtained numerically as a charge density at the molecular surface of the solute. w x Rauhut et al 18 combined dielectric solvation with semiempirical molecular orbital theory.…”