[gmx-users] dielectric constant

[s8026264]

Dear All


I am confuse.Buecuse you suggest a value for dielectric constant of SPC when

We use reaction field or generalized reactiom field  method (epsilon_r = 78 ) 

but I know about a paper that pepole found another value for dielectric 

constant of SPC.This valus is 54.

This paper and its abs. is :

Consistent dielectric properties of the simple point charge and extended
simple point charge water models at 277 and 300 K

Paul E. Smith and Wilfred F. van Gunsteren Department of Physical Chemistry,
Swiss Federal Institute of Technology Zürich, ETH-Zentrum, 8092 Zürich,
Switzerland

(Received 14 September 1993; accepted 8 November 1993)

The dielectric constants (epsilon) of the simple point charge (SPC) and
extended simple point charge (SPC/E) models of liquid water have been
determined at 277 and 300 K using a reaction field (epsilonRF) treatment for
the long-range electrostatic interaction. Consistent dielectric constants are
obtained by using statistical mechanical perturbation theory, such that the
properties of the system correspond to epsilonRF=epsilon, and are therefore
representative of a true infinite system. The dielectric constants of SPC were
determined to be 55.8 and 54.0 at 277 and 300 K, respectively, while the
dielectric constants of SPC/E were 68.5 and 62.3 at 277 and 300 K,
respectively. The Journal of Chemical Physics is copyrighted by The American
Institute of Physics. 





Sincerely yours


Mojtaba Alaei