CHEM01200604005 A. K. Pathak - Homi Bhabha National Institute
CHEM01200604005 A. K. Pathak - Homi Bhabha National Institute
CHEM01200604005 A. K. Pathak - Homi Bhabha National Institute
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E int-is = 0.171 + 0.129.n,<br />
when E int-is is expressed in eV and n is the number of solvent CO 2 molecules. This linear<br />
fitted plot has correlation coefficient > 0.99. The linear relation suggests that the average<br />
interaction energy between the anionic solute and a solvent CO 2 molecule is ~ 129 meV<br />
at MP2 level.<br />
On subtracting the ion-solvent interaction (E int-is ) from the solvent stabilization<br />
energy (E stab ) of each cluster, the solvent-solvent interaction energy (E int-ss ) can be<br />
evaluated. The calculated solvent-solvent interaction energy (E int-ss ) of I •− 2 .nCO 2 (n=1-10)<br />
is tabulated in Table 7.1. The variation of E int-ss with size of the cluster (n) is also shown<br />
in Fig. 2-I(c).<br />
As the solvent CO 2 molecules are far apart, the calculated solvent-solvent interaction<br />
energy is close to zero for I •− 2 .nCO 2 clusters (n≤4). For higher clusters the same increases<br />
asymptotically. In the present case, the solvent-solvent interaction energy has dispersion<br />
nature and originated from dipole induced dipole-dipole interaction of solvent CO 2<br />
molecules. It is worth to mention that the calculated interaction energy between two<br />
solvent CO 2 molecules is ~ 85 meV in case of neutral (CO 2 ) n clusters (n=1-3) at MP2/6-<br />
311+G(d) level of theory. The energy parameters for mono- and di- solvated clusters are<br />
also calculated applying CCSD(T) method and the values are listed in Table 7.1. It is<br />
worth to mention that basis set superposition error (BSSE) calculated for di-solvated<br />
cluster, I •− 2 .2CO 2 following counterpoise method is less than 5% and the same for monosolvated<br />
cluster, I •− 2 .CO 2 is about 12%. 45<br />
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