Does fix recenter affect on pressure tensor?

LAMMPS LAMMPS Mailing List Mirror
1

Hi everybody

I’m going to calculate the interfacial tension (IFT) of a system consists of a group of molecules sandwiched by other matter.

However, I noticed a drift in my case and I think using fix recenter may remove any unwanted drift.

So, I have a question:

Does using fix recenter impact on the calculation of pressure tensor?

I concern with that issue since IFT is obtained by main elements of the pressure sensor.

Many thanks in advance.

2

Hi everybody

I'm going to calculate the interfacial tension (IFT) of a system consists of a group of molecules sandwiched by other matter.

However, I noticed a drift in my case and I think using *fix recenter* may remove any unwanted drift.

no, it doesn't. it just recenters your coordinates, so you don't see it.

axel.

3

Thanks Axel.

According to your reply, using fix recenter is a tricky way to cancel the drift while obtaining correct values for IFT.

Am I right?

With Kind Regards

Saeedi Dehaghani Amir Hossein
Assistant Professor
Department of Petroleum Engineering
Faculty of Chemical Engineering

Tarbiat Modares University

Address: Tarbiat Modares University, Jalal Ale Ahmad Highway, Gisha Bridge, Tehran, Iran
Mob: +98-9122892230

Tel: +98 21 82883350
Fax: +98 21 82883350

4

Thanks Axel.

According to your reply, using *fix recenter* is a tricky way to cancel the drift while obtaining correct values for IFT.

Am I right?

no.

5

Axel, I’m really confused!!

Could I obtain correct IFT while using fix recenter?

You firstly said that fix would not impact on pressure calculation.

With Kind Regards

Saeedi Dehaghani Amir Hossein
Assistant Professor
Department of Petroleum Engineering
Faculty of Chemical Engineering

Tarbiat Modares University

Address: Tarbiat Modares University, Jalal Ale Ahmad Highway, Gisha Bridge, Tehran, Iran
Mob: +98-9122892230

Tel: +98 21 82883350
Fax: +98 21 82883350

6

Axel, I'm really confused!!

Could I obtain *correct* IFT while using *fix recenter*?

You firstly said that fix would not impact on pressure calculation.

no. i didn't say that. i only said, that fix recenter does *not*
remove the drift. it just hides it.

axel.

7

Thanks, Axel.

To summarize our discussion for other researchers, please confirm the following statement:

“fix recenter is a way to hide system drift while not affecting the calculation of pressure tensor”

Lastly, I concerned with the compatibility of “fix recenter” and fix NPT. Because latter adjust volume and particles positions at every timestep and former may intervene in that process.

With Kind Regards

Saeedi Dehaghani Amir Hossein
Assistant Professor
Department of Petroleum Engineering
Faculty of Chemical Engineering

Tarbiat Modares University

Address: Tarbiat Modares University, Jalal Ale Ahmad Highway, Gisha Bridge, Tehran, Iran
Mob: +98-9122892230

Tel: +98 21 82883350
Fax: +98 21 82883350

8

No, I never made any statement about the pressure tensor. You keep implying things that I never said, and that make no sense in the first place.

It is pretty self-evident, that when you do not remove a drift, your trajectory is garbage, unless you want to simulate a flow, and thus it is not worth looking at it for any purpose.

No means no. Full stop. This is going to be my last reply. Do as you like, but don’t claim that I am approving anything.

Axel