Thread: [Apbs-users] the real issue is whether any force field describes
Biomolecular electrostatics software
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From: Bob E. <bei...@ru...> - 2008-06-05 12:55:03
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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: bei...@ru... 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 Email: bei...@ru... Voice: +312-942-6467 FAX: +312-942-8711 FAX to Email: +801-504-8665 Department WebSite: http://www.rushu.rush.edu/molbio/ Personal WebSite: http://www2.phys.rush.edu/RSEisenberg/physioeis.html |