[lammps-users] initialisation variable

Dear Lammps Users,

I am trying to initialize the component pxz of the pressure tensor. I tried but it does not seem that it is working.

Why do I want to do that?
I want to do some shear test using npt. Increasing the pressure from 0 to 1, relaxing for 100 ps, and then increase the pressure again from 1 to 2. So, I want to save the pressure tensor to restart from the exact stress state.

Why is it not working?
I attached the input file.

As you can see, you have the lines:

run 0
variable p equal press
variable p3 equal pzz
variable p4 equal pxy
print "Initial pressure = $p"
print "Initial PZZ = $p3"
print "Initial PXY = $p4"
variable pixy equal $p4

I naively thought that I will have: pzz .ne. pxy .ne. pressure

here are the results:
Step Press Pzz Pxy p4 pixy
        0 479.94266 98.610877 -87.626451 -87.626451 479.94266
       10 3541.9246 3162.7305 -1689.8199 -1689.8199 479.94266

p4 changed which is okay and pixy is constant. However, p4 and pixy should be equal at step 0 and pixy should not be equal to Press.

It look like that all the component of the pressure tensor were initialized with the same quantity. Could you please confirm that? and if it is not the case, could you tell me how I could have access to those quantities.


Input file: