AMBER Archive (2006)

Subject: AMBER: strange temperature behavior when changing to constant pressure

From: Joshua (jb1978j_at_excite.com)
Date: Thu Nov 09 2006 - 13:52:33 CST

Dear AMBER users,

I am working with a system that I heated to 300 K at constant volume using ntt=3. The final temperature of this run was 300.11 K. I then input the restrt file from this run into a constant pressure run with temp0=300 and ntt=3. The constant pressure run showed some strange temperature behavior. When I set ntpr=1 to watch the temperature closely, it showed a temperature of 300.16 K at the first step, but the temperature quickly dropped down to about 295 K after .1 ps, and then gradually increases after .1 ps. I am stumped as to what could be causing this behavior (and whether I should even be worried about it). My first thought was that the change to constant pressure, and the corresponding increase in density, could cause this behavior, but the density increases steadily during the period in which the temperature decreases and then increases, so I can't imagine what the correlation would be.

I would really appreciate any suggestions on what might be going on here, and whether it's something that I should worry about.

Thanks,
Josh

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