Partial molar volumes for hard-sphere cavities in TIP4P water were computed running Monte Carlo simulations in the isothermal, isobaric (NPT) ensemble at 298 K and 1 atm. The explored size range goes from very small cavities up to cavities with a radius of 10 Angstrom. The excess volumes extracted from these data show a nonideal contribution that changes sign for a radius between 8 and 10 Angstrom. The same behavior was also found by computing the quantity directly from distribution functions by means of the Kirkwood-Buff integrals. The results are analyzed also in terms of hydration shell models which are based on the truncation of the Kirkwood-Buff integrals at the distances of the minima of the radial distribution functions. Another choice of truncation based on the oscillatory behavior of the excess volume as a function of the cutoff radius is also considered.
Nonideal Effects on the Excess Volume from Small to Large Cavities in TIP4P water
FLORIS, FRANCA MARIA
2004-01-01
Abstract
Partial molar volumes for hard-sphere cavities in TIP4P water were computed running Monte Carlo simulations in the isothermal, isobaric (NPT) ensemble at 298 K and 1 atm. The explored size range goes from very small cavities up to cavities with a radius of 10 Angstrom. The excess volumes extracted from these data show a nonideal contribution that changes sign for a radius between 8 and 10 Angstrom. The same behavior was also found by computing the quantity directly from distribution functions by means of the Kirkwood-Buff integrals. The results are analyzed also in terms of hydration shell models which are based on the truncation of the Kirkwood-Buff integrals at the distances of the minima of the radial distribution functions. Another choice of truncation based on the oscillatory behavior of the excess volume as a function of the cutoff radius is also considered.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
