6.2.2. Definition of Effective Properties 3064 6.3. Response Properties to Magnetic Fields 3066 6.3.1. Nuclear Shielding 3066 6.3.2. Indirect Spin−Spin Coupling 3067 6.3.3. EPR Parameters 3068 6.4. Properties of Chiral Systems 3069 6.4.1. Electronic Circular Dichroism (ECD) 3069 6.4.2. Optical Rotation (OR) 3069 6.4.3. VCD and VROA 3070 7. Continuum and Discrete Models 3071 7.1. Continuum Methods within MD and MC Simulations 3072

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Quantum mechanical continuum solvation models.

We present the full implementation of the integral equation formalism (IEF) we have recently formulated to treat solvent effects. The method exploits a single common approach for dielectrics of very different nature:  standard isotropic liquids, intrinsically anisotropic media like liquid crystals, and ionic solutions. We report here an analysis of its both formal and technical details as well as some numerical applications addressed to state the achieved generalization to all kinds of molecular solutes and to show the equally reliable performances in treating such different environmental systems. In particular, we report, for isotropic liquids, data of solvation free energies and static (hyper)polarizabilities of various molecular solutes in water, for anisotropic dielectrics, a study of an SN2 reaction, and finally, for ionic solution, a study of some structural aspects of ion pairing.

Evaluation of Solvent Effects in Isotropic and Anisotropic Dielectrics and in Ionic Solutions with a Unified Integral Equation Method: Theoretical Bases, Computational Implementation, and Numerical Applications

We present a formal and numerical comparison between the iterative and matrix-inversion approaches of the polarizable continuum model. The formal analysis shows completely the equivalence of the two approaches. Numerical equivalence is also recovered, introducing in both methods the proper boundary conditions on the apparent charge distribution. © 1995 John Wiley & Sons, Inc.

Remarks on the use of the apparent surface charges (ASC) methods in solvation problems: Iterative versus matrix‐inversion procedures and the renormalization of the apparent charges

Davydov’s Soliton

A quantum-mechanical reaction field theory of solvent effects is proposed. It contains as a limiting case Onsager's model. It leads to an effective, non-linear, hamiltonian for the molecule in solution and hence to a tool for studying changes in charge distributions and molecular properties. Numerical examples are given.

Self-consistent reaction field theory of solvent effects

We have studied some dynamical properties of the protons in one-dimensional H-bonded system whose polarization field Hamiltonian is strongly anharmonic. We find solitary wave solutions. Kink and antikink solutions correspond to ionic D t default (H 3 O + ) and ionic L t default (OH - ), respectively. Thus ionic defaults are described as solitary excitations in H-bonded systems.

Dynamics of the Protons in One-Dimensional Hydrogen-Bonded Systems

The excited equilibrium state of molecular complex in solution is described by the use of the nonlinear Schrodinger equation presented in our previous paper. The excited equilibrium state of charge-transfer molecular complex or the equilibrium state of exciplex in polar solvents is quite polar and quite different from the excited Franck-Condon state, and has large tendency to dissociate to solvated ions. These theoretical results are confirmed by the laser photolysis experiments on the excited states of the molecular complexes.

Theory of the excited state of molecular complex in solution

We have studied again the dynamical properties of protons in one-dimensional H-bonded system, taking account of the coupling between the proton motion and the lattice deformation. We find that the solitary waves of the proton-polarization are accompanied by the local lattice-deformations. Kink and antikink solutions correspond to ionic D t default (H 3 O + ion) and L t default (OH - ion), respectively. Two modes of solitary waves and two modes of phonons are found in the four respective regions of wave velocities.

Solitary Waves in One-Dimensional Hydrogen-Bonded Systems

In order to investigate the feature of the charge-transfer molecular compound forme:! in biological environment, we develop a simple theory on the charge-transfer molecular compound in a local field; the polarization or the dipole moment, the binding energy and the maximum wave length and the oscillator strength of the spectrum are estimated as functions of the strength of the local field. In the biological system the local field consists of the Coulombic field due to free charges and permanent dipoles in the structural biopolymers and the reaction field due to the polarization induced in the sur­ rounding medium by the dipole moment of the compound. By the additional effect of these two sorts of local fields the compound in biological system can be polarized strongly. Especially, an interesting phenomenon can be expected where the polarization and the absorption maximum change discontinuously for the variation of the Coulombic field or the dielectric constant of the medium. Such a strongly polarized state is considered as the first important stage of the biochemical reaction and the abrupt polarization in­ itiated by a small change of the Coulombic field or of the dielectric constant of the surroundings seems to suggest a control mechanism in the biological functions.

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Charge-Transfer Molecular Compounds in Biological Systems

The basic equation to determine the equilibrium electronic structure ψ of the solute system (the solvated electron or the solute molecule or the solute molecular complex) in polar solvent is proposed in the form of variational equation δ( F t (ψ)-κ f )=0 which states that the free energy of the total system F t (ψ) consisting of the solute system and the solvent is minimum for an arbitrary variation of ψ in accordance with the normalization condition f = -1=0; here κ denotes a Lagrange undetermined multiplier. The nonlinear wave equations derived from the basic equation for the dimeric molecules or their radicals yield the broken symmetry solutions (self-trapping states). The simple description of the solvated electron is presented as another example of the application of the basic equation.

Sigeo Yomosa

Papers

Dynamics of the Protons in One-Dimensional Hydrogen-Bonded Systems

Theory of the excited state of molecular complex in solution

Solitary Waves in One-Dimensional Hydrogen-Bonded Systems

Charge-Transfer Molecular Compounds in Biological Systems

On the Basic Equation for the Equilibrium Electronic States in Polar Solvents —Broken Symmetry—