Re: Boiling temperature of water.

From: Boyang Wang (
Date: Thu Jun 22 2006 - 21:38:54 CDT

 Hi Jindal,
 Thanks for the reply. After a long time ~300 ps, I see that the water box becomes several times bigger than at lower temperatures. This means the water seems to be boiling. Maybe it takes a long time for the box to expand into a much larger box, which means boil into vapor, for example, nanoseconds.
 Thanks again for your time.

Jindal Shah <> wrote: Hello Boyang,

This is normal. There are a few reasons why you may not see boiling.

The TIP3 model may have a different boiling point than the experimental value ( i would guess much higher).

If you calculate vapor density of water at 400 K, it is much less than the bulk density and you would require a much larger box!


On 6/22/06, Boyang Wang <> wrote: Hi all,
 I have a quick question. When I run NPT simulation of liquid water by NAMD, the water box does not boil into gas phase, even at about 400K or higher. Why is it so?
 I am puzzled. Is that due to lack of hydrogen bonding?
 Simulation details:
 A water box is equilibrated for 100ps after minimization. The TIP3 model was used for the water molecules. Langevin Piston method was used, with a pressure 1.0 bar. Langevin dynamics was applied, with damping coefficient 0.01, constant temperature 500K. PME periodic electrostatics was also used.
 Thanks for your time and have a nice summer.




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