movement stopping in NPT simulation after NVT?

Dear all

In a liquid/liquid I am simulating once I start NPT simulation after NVT I see the movement of the interface even if I use the following command before NPT part.

velocity all zero linear

I would appreciate if I have your advice to solve the problem.

Thanks,
Best,
Saly

The velocity command sets atom velocities one time.

When you then run dyanmics, velocities will become

whatever they want to be, due to forces.

Steve

The velocity command sets atom velocities one time.
When you then run dyanmics, velocities will become
whatever they want to be, due to forces.

​thus you'd need something more permanent, e.g. applying fix spring in
tether mode with a weak spring constant to a group of atoms from one set of
molecules​

​axel.​

1- This command have to be applied both in equilibration and production steps (or only in the fist one)?

2- I need to have the value of pressure tensor components in my system to calculate the liquid/liquid interfacial tension. Does applying this command lead to change the results?

thanks
Best,
Saly

1- This command have to be applied both in equilibration and production
steps (or only in the fist one)?

​both.​

2- I need to have the value of pressure tensor components in my system to
calculate the liquid/liquid interfacial tension. Does applying this command
lead to change the results?

it will have an impact, but by how much is ​impossible to predict. it
should be a very weak tether and thus may not even show.

​but if you have a drifting system, that will have an impact as well as
your temperature will be off (and again, the question is: by how much).

the best solution would be to figure out what is causing the drift and
eliminating that...

axel.