INDO-SCRF

Recently, Rosch and Zerner published a paper describing a perturbation method with the use of sum rules to examine the solute-solvent dispersion contribution in solvatochromic shift within the INDO-SCRF model.2 2,278 jhe method makes use of separate calculation of the solute and solvent in the continuum solvent and combines the results to evaluate dispersion interactions. The theory was successfully applied to acetone, benzene, naphthalene, and chrysene in cyclohexane, which all show large red absorption shifts relative to the gas phase spectra. Within the same spirit, the method may be applied to correct the results predicted by combined QM-CI/MM simulations. 

Mitchell, C.D. and Netzel T.L., CIS INDO/S SCRF study of electron transfer excige states in a 1-pyrenyl substituted l-methyluracil-5-carboxamide nucleoside dielctric continuum solvation effects on electron transger states. J.Phys.Chem. B (2000) 104 125—136. 

Other semiempirical Hamiltonians have also been used within the BKO model. A Complete Neglect of Differential Overlap (CNDO/2) ° study of the effect of solvation on hydrogen bonds has appeared. o The Intermediate Neglect of Differential Overlap (INDO) °2 formalism has also been employed for this purpose.2011 Finally, the INDO/S model,which is specifically parameterized to reproduce excited state spectroscopic data, has been used within the SCRF model to explain solvation effects on electronic spectra.222,310-312 jhis last approach is a bit less intuitively straightforward, insofar as the INDO/S parameters themselves include solvation by virtue of being fit to many solution ultraviolet/visible spectroscopic data.29J... 

Among the few determinations of of molecular crystals, the CPHF/ INDO smdy of Yamada et al. [25] is unique because, on the one hand, it concerns an open-shell molecule, the p-nitrophenyl-nitronyl-nitroxide radical (p-NPNN) and, on the other hand, it combines in a hybrid way the oriented gas model and the supermolecule approach. Another smdy is due to Luo et al. [26], who calculated the third-order nonlinear susceptibility of amorphous thinmultilayered films of fullerenes by combining the self-consistent reaction field (SCRF) theory with cavity field factors. The amorphous namre of the system justifies the choice of the SCRF method, the removal of the sums in Eq. (3), and the use of the average second hyperpolarizability. They emphasized the differences between the Lorentz Lorenz local field factors and the more general Onsager Bbttcher ones. For Ceo the results differ by 25% but are in similar... 

Figure 1. Dependence of the AMI SCa SCRF Calculated Electrostatic Solvation Energies (E), INDO/1 SCa Calculated Dispersion Energies (D) and SPT Spherical Cavity Formation Free Energies (C) on the Cavity Radius for Methanol (a) and Acetonitrile (b).

The calculated individual contributions to the total aqueous solvation free energies of 30 organic compounds are given in Table 1. The electrostatic (SCRF) contributions were calculated using semiempirical AMI (Austin Model 1 [60,61]) method. The dispersion energies were calculated using INDO/1 parameterization [62] and AMI optimized molecular geometries in solution. A comparison of different columns in Table 1 with the experimental solvation... 

AMI SCRF Calculated Electrostatic Solvation Energies, Eei, INDO/1 Calculated Dispersion Energies, Edisp, SPT Cavity Formation Free Energies, AGcav, and Experimental Solvation Free Energies, AG(exp) (kcal/mol), [63] of 30 Organic Compounds in Aqueous Solution. 

Kucharski et al.161 have calculated the static / -hyperpolarizability of new sulphonamide amphiphiles using finite field SCF and INDO/S methods. In the latter case a solvent correction (SCRF option) was also included. The ab initio and INDO/S results for the isolated molecule were similar while the inclusion of the solvent correction increased the values by about 55-65%. Kassimi and Lin 168 have calculated the dipole moment and static polarizability of aza-substituted thiophene derivatives within the Hartree-Fock approximation. For a representative sub-set, correlation up to the MP4(SDQ4) level has been included. The results are expected to be accurate to within a few percent. 

Table 11.1.3. INDO/S SCRF Cl calculated and experimental spectroscopic transition energies of some dyes in different solvents ...

The INDO/S SCRF Cl method has been also successfully applied for the prediction of the solvatochromic shifts in various nitro-substituted porphyrins. ... 

Table 11.1.6. The INDO/S SCRF/CI calculated and experimental spectral transition energies in different solvents for azoles (cm ) ...

Onsager s SCRF is the simplest method for taking dielectric medium effects into account and more accurate approaches have been developed such as polarizable continuum modes, " continuum dielectric solvation models, - explicit-solvent dynamic-dielectric screening model, - and conductor-like screening model (COSMO). Extensive refinements of the SCRF method (spherical, elliptical, multicavity models) in conjunction with INDO/CIS were introduced by Zerner and co-workers ° as well. 

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