In my view, the central issue is whether *any* force field describes
concentrated salt solutions correctly.
The key thermodynamic variable of an ionic solution
is the free energy per mole (called 'activity' in the
physical chemistry books).
The number density of ions near DNA is of the
order of 10 Molar compared to a water number
density (same units) of about 55 Molar.
The question is whether any force field and MD
method calculates the free energy mole approximately
right for such a concentrated solution.
In fact, one probably should view the ions near DNA
as an ionic liquid closer to a melted salt than to
a normal aqueous solution
Return Address for email: beisenbe@...
Bob aka RS Eisenberg
Bard Professor and Chairman
Dept of Molecular Biophysics & Physiology
Rush Medical Center
1653 West Congress Parkway
Chicago IL 60612 USA
Office Location: Room 1291 of
Jelke Building at 1750 West Harrison
FAX to Email: +801-504-8665
Department WebSite: http://www.rushu.rush.edu/molbio/
Personal WebSite: http://www2.phys.rush.edu/RSEisenberg/physioeis.html