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Title: Comment on Mean force potential for the calcium--chloride ion pair in water'' [J. Chem. Phys. 99, 4229 (1993)]

Journal Article · · Journal of Chemical Physics; (United States)
DOI:https://doi.org/10.1063/1.468572· OSTI ID:6562597
;  [1]
  1. Environmental Molecular Sciences Laboratory, Pacific Northwest Laboratory, Richland, Washington 99352 (United States)

The interionic potential of mean force (pmf) for the Ca[sup ++]--Cl[sup [minus]] ion pair in water is computed using the molecular dynamics computer simulation technique. The calculated pmf indicates a stable contact pair (CIP) and a solvent-separated pair (SSIP) centered at 2.9 and 5.0 A with a 2.8 kcal/mol barrier to dissociation. The SSIP well is about 2.0 kcal/mol deeper than the CIP suggesting that water molecules in the first hydration shell are strongly coordinated to the Ca[sup ++] ion. Our results do not agree with the pmf reported recently by Guardia, Robinson, Padro [J. Chem. Phys. [bold 99], 4229 (1993)]. Possible reasons for the discrepancy are discussed.

DOE Contract Number:
AC06-76RL01830
OSTI ID:
6562597
Journal Information:
Journal of Chemical Physics; (United States), Vol. 102:8; ISSN 0021-9606
Country of Publication:
United States
Language:
English