units in npT

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1

Hello everybody,

I am trying to figure out the units in NpT ensemble.

units lj
fix 2 all npt temp 300.0 300.0 100.0 iso 0.1 0.1 1000

I guess are the two relevant lines -> in any case I attach the reproducible code.

So: I make my code write the Temperature. What I find is something fluctuating around 1e-06. From the units section of tutorial [http://lammps.sandia.gov/doc/units.html] I understand that units are dimensionless and set to 1 - at least the fundamental.

Then I read that the unit of pressure is sigma^3/epsilon, and sigma=1, epsilon=1. OK so why am I finding 1e-06 if I have put 300 as input pressure? Am I perhaps misunderstanding something?

Thanks for any help

Regards

Mario

in.pour (1.28 KB)

2

Hello everybody,

I am trying to figure out the units in NpT ensemble.

units lj
fix 2 all npt temp 300.0 300.0 100.0 iso 0.1 0.1 1000

I guess are the two relevant lines -> in any case I attach the reproducible
code.

So: I make my code write the Temperature. What I find is something
fluctuating around 1e-06. From the units section of tutorial
[http://lammps.sandia.gov/doc/units.html] I understand that units are
dimensionless and set to 1 - at least the fundamental.

Then I read that the unit of pressure is sigma^3/epsilon, and sigma=1,
epsilon=1. OK so why am I finding 1e-06 if I have put 300 as input pressure?

you have set 300 as target *temperature* and 0.1 as pressure.

Am I perhaps misunderstanding something?

probably how a nose-hoover thermostat works in general. there have
been numerous discussions of it in the past. have a look at the
mailing list archives.

axel.