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Re: [lammps-users] The difference between compute pressure and compute stress/atom
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Re: [lammps-users] The difference between compute pressure and compute stress/atom


From: Axel Kohlmeyer <akohlmey@...24...>
Date: Sun, 27 Aug 2017 16:18:20 -0400



On Sat, Aug 26, 2017 at 11:41 PM, 709832702 <709832702@...3079......> wrote:

Hi,

Recently, I adopted the compute pressure and compute stress/atom to calculate normal stress under uniaxial tensile as shown in the attached Figure, here the tensile direction is with the periodic boundary, and the other two direction are the free surface, I found that the stresses are not equal at the beginning, although they are in agreement at the end of progress, so what is the reason, they are all based on the virial theory. I also test under all three directions are the periodic boundaries, this time they are nearly coincident.

first rule about ​figures in science: *always* include units! 

since you don't explain with sufficient detail what you are computing for the figure, there is little to comment. if you did it correctly, both graphs should be identical, since they should show the identical information. the fact, that they don't coincide hints at you don't computing one of them correctly.

axel.



 

Best wishes!


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--
Dr. Axel Kohlmeyer  akohlmey@...12...24...  http://goo.gl/1wk0
College of Science & Technology, Temple University, Philadelphia PA, USA
International Centre for Theoretical Physics, Trieste. Italy.