AMBER Archive (2004)

Subject: AMBER: parameters-DGnp

From: John (
Date: Wed Sep 01 2004 - 19:25:03 CDT



Trying to represent the nonpolar contribution to salvation energy having as
solvent DMSO I have to decide on the and b parameters of the relationship
that links the DGnp with the SAS area. I have found the surface tension
parameter in J. A. Riddick, W. B. Bunger, and T. K. Sakano, Organic
Solvents: Physical Properties and Methods of Purification (Wiley, New York,
USA, 1986). The unit for the surface tension in various temperatures is mN/m
in the text book and covers the range around 0.0713-0.0518. The surface
tension in Amber is 0.005 kcal/mol*A2. Working back from the surface tension
given by Amber to get the units given by the text book I end up with the
figure 0.0034mN/m. This figure is not in the range given by the text book.
This is probably due to the fact that the surface tension in Amber is a best
fit unitary parameter.


The reason I went down this route is that I cannot find best fit values in
the case of DMSO. I was hoping to get my parameters using the ratio between
water and DMSO and assuming linear dependancy. But, provided that my
calculations and my logic are correct, I cannot decide on a surface tension
for DMSO.


I have not also found any value for the b parameter for DMSO.


Any comments and suggestions to tackle this issue will be much appreciated.


Best wishes,




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