CHEM01200604005 A. K. Pathak - Homi Bhabha National Institute

80
Cl 2
.nH 2
O (n=1-8)
80
Br 2
.nH 2
O (n=1-8)
Energy (kcal/mol)
60
40
20
E solv
E int
Energy (kcal/mol)
60
40
20
E solv
E int
0
0 2 4 6 8
n
0
0 2 4 6 8
n
A
B
Energy (kcal/mol)
80
60
40
20
I 2
.nH 2
O (n=1-8)
E solv
E int
0
0 2 4 6 8
n
C
Fig. 4.2. Plot of calculated interaction energy, E int and solvent stabilization energy, E solv at MP2/6-
311++G(d,p) level in kcal/mol vs. n, number of water molecules for (A) Cl 2 .nH 2 O, (B) Br 2 .nH 2 O and (C)
I 2 .nH 2 O clusters.
The interaction energy (E int ) is the measure of the interaction between the halogen
moiety and water units. Thus, a large value of E int indicates the presence of a large
number of water molecules in close surrounding of the halogen moiety. For the present
systems, calculated E int is small and does show only a small increase with the addition of
water molecules. That explains the presence of only a few water molecules (2–3) in the
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