AMBER Archive (2003)

Subject: RE: question on EWALD

From: Yong Duan (yduan_at_udel.edu)
Date: Mon Feb 17 2003 - 15:08:17 CST

Dear Sichun,

You probably have stated this before, but I did not catch it. Anyhow,
how long has your system been stable at 500K under NPT?
I gather you are using TIP3P or SPC/E type solvent. In either case, the
system can be relatively unstable because TIP3P vaporizes at roughly
round 400K. If that is the case, you probably should see systematic
increase in the volume (not the pressure, which is under control). If
you intend to simulate solution phase, it may be a good idea to use NVT
instead. The trick is that you may need to "equilibrate" the system at a
lower temperature using NPT (to maintain reasonable density). You will
then switch to NVT at 500K.

yong
******
In fact, the temperature I used is 500K with constant pressure. Is that
necessary to run constant volume to
equilibrate to 500K before I perform constant pressure? I am confused.