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Re: [ESPResSo-devel] Pressure calculation / P3M stress tensor
From: |
Axel Arnold |
Subject: |
Re: [ESPResSo-devel] Pressure calculation / P3M stress tensor |
Date: |
Fri, 3 Apr 2009 16:09:34 +0200 |
User-agent: |
KMail/1.7.1 |
Am Freitag 03 April 2009 15:13 schrieb Kai Grass:
> Hi,
>
> can someone tell me if the warning issued by the pressure calculation
> that the P3M stress tensor is not implemented (pressure.c, line 176)
> is obsolete? There definitely is some code in that section ...
No, the warning is not obsolete. The stress _tensor_ is not calculated. What
that routine does, is distributing the isotropic pressure onto the trace of
the pressure, rather than really calculating the stress tensor. Therefore,
only the _isotropic_ pressure calculated from the tensorial one is correct.
Implementing the stress tensor for P3M would be quite a bit of work, and as
far as I remember, involves a _lot_ of Fourier transforms.
Axel
--
Dr. Axel Arnold
Fraunhofer SCAI
Schloss Birlinghoven, 53754 Sankt Augustin, Germany
Tel: +49 2241 14 2575