how to convert CHARMM TIP3P to traditional TIP3P

From: subbarao kanchi (ksubbu85_at_gmail.com)
Date: Wed Mar 06 2013 - 05:56:27 CST

Dear NAMD users,
                          I searched in literature and discussion in NAMD
Mailing List, I come to know that the water model used in CHARMM FF is
Modified TIP3P. IN this modified TIP3P there are Non bonded Lennard Jones
interactions in between water Hydrogen atoms but not in traditional TIP3P
model.I Have following doubts regarding water models.

1) I know that the CHARMM FF (for bio molecules like lipid and proteins)
parameters are developed by treating TIP3P water model But I can’t able to
find reason for introduction of Lennard Jones interactions in between water
Hydrogen atoms.

2) If I want to run MD simulations with traditional TIP3P, Is it enough to
avoid the Lennard Jones interactions in between water Hydrogen atoms by
using NBFIX ?

3) I want to MD simulations of water and solid surface, which is good
force field to use among regular TIP3P and CHARMM modified TIP3P? or Is it
possible to used other water force field like SPC/E in NAMD ?

Thanks in advance, if I get any suggestions.

Regards,
subbu.

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