problem with fravity

LAMMPS LAMMPS Mailing List Mirror
1

Hello Dear

I going to use gravity(9.8) in my simulation. I’m simulating Argon with lj unit. In this simulation, Argon is used as a Lennard-Jones fluid with the following potential parameters:

Energy parameter (epsilon) =1.67*10^-21 J

Length parameter (sigma) =3.4*10^-10 M

Mass=6.63*10^-26 Kg

I tried to use unitless gravity with this formula:

Unitless gravity= (gravitysigmamass)/epsilon

ð Unitless gravity = gravity*(1.35*10^ -14)

Then I used command below for gravity:

fix G flow gravity 1.323*10^-13 vector 0 -1 0

Are unitless formulas and command true?

Thanks for your help

2

Hello Dear

I going to use gravity(9.8) in my simulation. I’m simulating Argon with lj
unit. In this simulation, Argon is used as a Lennard-Jones fluid with the
following potential parameters:

Energy parameter (epsilon) =1.67*10^-21 J

Length parameter (sigma) =3.4*10^-10 M

Mass=6.63*10^-26 Kg

I tried to use unitless gravity with this formula:

Unitless gravity= (gravity*sigma*mass)/epsilon

ð Unitless gravity = gravity*(1.35*10^ -14)

Then I used command below for gravity:

fix G flow gravity 1.323*10^-13 vector 0 -1 0

Are unitless formulas and command true?

you have to test this yourself. this is not the "please check my math"
mailing list.

apart from that. what is the point to add such a tiny force?

axel.