MONTE CARLO SIMULATION OF I-, Br-, AND Cl- IN WATER USING AB INITIO PAIR POTENSIAL FUNCTIONS
ABSTRACT: Monte Carlo
simulations were performed for I-, Br- and Cl-, in water using ab initio pair
potential. The systems consisting of one anion in 215 solvent molecules have
been simulated at 298 K. Anion-water pair potentials have been newly developed
based on ab initio calculations of split valence basis set plus polarization
quality. The structure of the solvated ion is discussed in terms of radial
distribution functions, coordination number and pair potential distribution.
Structural properties were investigated by means of radial distribution
functions and their running integration numbers, leading for the first
solvation shell to an average 12.60 H2O around I- with I--O distance of 3.74 Å
and I--H distance of 2.86 Å, 11.84 H2O around Br- with Br--O distance of 3.40 Å
and Br--H distance of 2.42 Å, and 10.68 H2O around Cl- with Cl--O distance of
3.20 Å and Cl--H distance of 2.24 Å, respectively. The structure of the
water-anion complexes are agreed with dipole orientation. Pair energy
distribution of hydrated anions showed that the pair interaction energy are
increase from I-, Cl-, to Br-, namely, -6.28, -9.98 and -13.67 kcal/mol,
respectively. The coordination number distribution analysis for the first
solvation shell of the all hydrated anions indicated a high exchange rate for
the first solvation shell ligands.
Author: Harno Dwi Pranowo
Journal Code: jpkimiagg070014
