Coordinate coupling solvation free energies

Rao and Singh32 calculated relative solvation free energies for alkyl- and tetra-alkylammonium ions using same conditions as described before for neutral molecules (except, atomic partial charges were not scaled for ions). The values obtained with coordinate coupling were in better agreement with... 

Figure 6, Normalized solvation free energy for the system of Fig. 5 as a function of the bath cutoff frequency, oi, and the two-level system coupling, J. Here an effective bath coordinate (EBC) was first included in the system and a variational polaron transformation applied to the resulting TLS-bath and EBC-bath couplings. The dashed lines indicate the minimum free energies obtained when only the TLS-bath coupling was treated by the second transformation the dotted line shows results when both were treated. The exact free energies are plotted with solid lines.

Fig. 2.5. Possible applications of a coupling parameter, A, in free energy calculations, (a) and (b) correspond, respectively, to simple and coupled modifications of torsional degrees of freedom, involved in the study of conformational equilibria (c) represents an intramolecular, end-to-end reaction coordinate that may be used, for instance, to model the folding of a short peptide (d) symbolizes the alteration of selected nonbonded interactions to estimate relative free energies, in the spirit of site-directed mutagenesis experiments (e) is a simple distance separating chemical species that can be employed in potential of mean force (PMF) calculations and (f) corresponds to the annihilation of selected nonbonded interactions for the estimation of e.g., free energies of solvation. In the examples (a), (b), and (e), the coupling parameter, A, is not independent of the Cartesian coordinates, x. Appropriate metric tensor correction should be considered through a relevant transformation into generalized coordinates...

Figure 3.45 Schematic free energy curves in the solvent coordinate z for the discussion of the equilibrium solvation location of the Cl seam in Figure 3.42 Solid curves are the adiabatic curves for very small but finite electronic coupling, while the dashed curves are diabatic curves for zero coupling, (a) The symmetric case, where the filled circle represents the location of the minimum free energy in the upper adiabatic state in the presence of finite electronic coupling, while the open circle represents a free energy minimum when the electronic coupling vanishes exactly (6 = 90°). (b) An asymmetric case where the two surfaces intersect for z > 1 and the equilibrium location of the Cl seam fails.

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