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Date: Thu, 18 Oct 2001 12:17:13 -0500 (CDT)
From: Vemparala Satyavani <vani:~at~:reef.phys.lsu.edu>
To: chemistry%!at!%ccl.net
Subject: TIP$P water model (fwd)
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Hi,

Thanks for all the help regarding my previous query. I incorporated the
TIP4P model. I have one question regarding the constraints in this model
of water.

To avoid the dynamics on the dummy particle ( as suggested in the GROMACS
site, thanks to David Va der Spoel and Paul van Maaren), iam
redistribuiting the forces on the dummy to the other three atoms. To do
this every time step, i compute the positions of the dummy particle before
passing all the coordinates to Ewald method. 

For the constraints part, i still have constraints only on OH, OH and HH
bond. Do i need constraints between dummy particle(M) and other three
atoms?

If i don't want to use the rigid model, can i use a flexible model for
TIP4P water? Can anyone give me some information about where i can get the
parameters for the flexible model of TIP4P model of water(AMBER has
parameters for TIP3P, i coudn't find parameters for TIP4P.)

Thanks
vani