CHEM01200604005 A. K. Pathak - Homi Bhabha National Institute

Where, E[I •− 2 .nH 2 O] is the energy of the optimized I •− 2 .nH 2 O cluster and E s [I 2 .nH 2 O] is
the single point energy of the I 2 .nH 2 O obtained by removing the extra electron from the
optimized I •− 2 .nH 2 O cluster. VDE is the energy required to remove an electron from the
anionic hydrated clusters. It is clearly observed that the conformer that has higher
interaction energy, E int has higher VDE in each size (n) cluster. The weighted average
VDE (VDE w ) is also calculated based on the statistical population of different conformers
for each size (n) cluster and displayed in Table 2.1. Fig. 2.6-I displays the plot of VDE w
vs. n showing the similar nature of shell closing at n=4 and n=8 as in case of E w
int
plot. It
is worthwhile to mention that the variation of weighted average vertical detachment
energy with the size of the cluster is similar for all other hydrated cluster, X. nH 2 O (X=
Cl •− 2 , Br •− 2 , CO •− 3 , NO − 3 and CO 2− 3 ).
As it is discussed, the plot of interaction energy (E int ) and vertical detachment
energy (VDE) vs. number of water molecules (n) in these hydrated clusters (I •− 2 .nH 2 O)
behave in a similar way. So it is interesting to test if there is any direct correlation
between these two energy terms. For I •− 2 .nH 2 O clusters (n=1-8), weighted average
interaction energy, E w
int
is related to the statistical weighted average vertical detachment
energy, VDE w by a simple linear relation,
E w
int
= -4.64 + 1.13 VDE w
Where, both E w
int
and VDE w are expressed in eV. The best fit linear plot with the
graphical data points are shown in Fig. 2.6-II(a).
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