Eigen cation

H2OH+ 3OH2 (first solvation shell for -290.22 [11] -287.7 [12[ N/A Eigen cation MP2... 

A second important application of CMD has been to study the dynamics of the hydrated proton. This study involved extensive CMD simulations to determine the proton transport rate in on our Multi-State Empirical Valence Bond (MS-EVB) model for the hydrated proton. = Shown in Fig. 4 are results for the population correlation function, (n(t)n(O)), for the Eigen cation, HsO, in liquid water. Also shown is the correlation function for D3O+ in heavy water. It should be noted that the population correlation function is expected to decay exponentially at long times, the rate of which reflects the excess proton transport rate. The straight line fits (dotted lines) to the semi-log plots of the correlation functions give this rate. For the normal water case, the CMD simulation using the MS-EVB model yields excellent agreement with the experimental proton hopping... 

Figure 4 Semi-log plot of the population correlation function for an Eigen cation in liquid water at 300 K. Shown are the water (solid line) and heavy water (dot-dashed line) results, and the bestfit (dotted line) to each.

Figure 22. Configurations of (a) ZundeP (H5O2 ) and (b) Eigen cation (H9O4 ). Black, oxygen atom white, hydrogen atom.

The minimum hydration number for the reaction to take place was chosen as four based on the Eigen cation stmcture and the details... 

Figure 23. Description of six geometric triggers required for structural diffusion (a) O -O separation must form a Zundel ion (b) O -H separation must exceed the equilibrium bond distance (c) Z0 H 0 is nearly linear in the Zundel ion (d) Lone pair of electrons in the water should point towards the proton (e) Initial H3O forms an Eigen ion (f) Eigen cation is formed around final H3O. These six geometric triggers must he satisfied along with the energetic trigger for the reaction to take place. O of H3O, gray O of H2O, black H, white.

The distribution of the first peak from the g(r) 0(H30 )-0(H20), H(H30 )-0(H30 ) in Zundel cation and 0(H30 )-0(H20) in Eigen cation Bond angles of Z0iH 02 and ZH3O2H from optimized isolated H5O2 structure. ... 

Figure 12.3. Global minimum energy structures determined by full optimization at the B3LYP/6-31G level of a trifluoromethanesulfonic acid molecule (a) and apara-toluene sulfonic acid molecule (b) each with 6 water molecules. Both acids show the dissociated proton exists as a solvent separated pair consisting of what resembles an Eigen cation and sulfonate ion. The 0-0 and 0-H (in brackets) distances for each acid reveal that aromatic anion is the stronger base. First presented in Ref. [23],...

THE IONIC BOND AND IONIC MATTER Eigen cation... 

In the initial state, shown on the left-hand side, the excess is proton localized on the Eigen cation, and the excess proton charge is centered at the position of the donor oxygen atom Od- The free energy profile of the proton as a function of 8jj+ exhibits a nonsymmetric double-well character. 

S., Leicknam, J.-C., and Vuilleumier, R. (2007) Time-resolved observation of the eigen cation in liquid water. /. Chem. Phys., 126, 034511. 

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