Hi Kitty,
As far as I know, Independent pressure scaling is achieved by keyword aniso…
Here, is the example…
fix 1 all npt 300 300 100 aniso 1.0 1.0 1.0 1.0 1.0 1.0 100.0
The NULL keyword means that no pressure is applied… the dimensions will not change…
Regards,
Vikas