<div>Yes. At vanish electric field, even with USPP the stress is the same as the normal calculation (without using Berry Phase method).</div>
<div>Hope this helps.</div>
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<div>Is your calculated stress OK with USPP at vaishing electric field?<br>SB<br><br>On Apr 1, 2009, at 4:48 PM, hanghui chen wrote:<br><br>> Dear PWscf developers and in particular Professor Baroni,<br>> Thank you very much for your instructions.<br>
> I did the test to check the forces and stress in the Berry<br>> phase method with the ultrasoft pseudopotential. The forces are<br>> correct but the stress is around 50% smaller. I am not sure whether<br>
> it is due to the ultrasoft pseudopotential or not.<br>> I would greatly appreciate it if the developers of QE could<br>> reexamine the calculation of stress in the Berry phase method with<br>> the ultrasoft pseudopotential.<br>
> Best wishes.<br>><br>> Hanghui Chen<br>> Department of Physics,<br>> Yale University<br></div>