[Pw_forum] maybe a bug in the QE 4.0.4

[hanghui chen]

Dear PWscf developers and in particular Professor Baroni,
      Thank you very much for your instructions.
      I did the test to check the forces and stress in the Berry phase
method with the ultrasoft pseudopotential. The forces are correct but the
stress is around 50% smaller. I am not sure whether it is due to the
ultrasoft pseudopotential or not.
      I would greatly appreciate it if the developers of QE could reexamine
the calculation of stress in the Berry phase method with the ultrasoft
pseudopotential.
      Best wishes.

Hanghui Chen
Department of Physics,
Yale University
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