[lammps-users] TIP4P and NPT

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1

Dear all,

I am trying to compute the density of water. For a start I have just used a
very small box consisting of 703 molecules. Using the NPT, I find that the
box size increases dramatically ( nearly 200 times larger in each
dimension), then reduces and increases again. The simulation becomes
extremely slow. I started off with the correct box size for the density of
water at 1 atm pressure, so I would expect to recover approximately this box
size.

Is there something wrong with my input ? I am using TIP4P to model the water
molecules. Attached are my input files

Thanks

Huck Beng

in.swnt_c (1.04 KB)

data.swnt (215 KB)

2

You're trying to do it in metal units. Have you done
it successfully in real units? Ahmed has test files
for TIP3P water in real units he can send you.

Steve

3

Or probably you would like to increase the Pdamp to a large value.