[Pw_forum] using the stress tensor to compute cell gradients

[Jessica McKinley]

To whom it may concern,

I am attempting to use the stress tensor to compute the gradient of my unit
cell.

Looking in your source code I noticed in move_ions.f90 you have the
following code around line 153:

IF ( lmovecell ) THEN
  CALL cell_force( fcell, - transpose(bg)/alat, sigma, omega, press )
END IF

At this point in your code you are in reciprocal space correct (since you
are using bg which is your reciprocal lattice vectors)? If so I'm operating
in direct space so I was wondering if you had any insight into how I would
compute this same quantity in cartesian? Also when I turn on tstress = true
is the stress tensor that is printed out in Cartesian space or in Crystal?

Best,
Jessica McKinley
UC Riverside
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