[Pw_forum] Is there a way to fix the c of supercell and vary only a and b

[Paolo Giannozzi]

I don't think the version of the code you are using
implements constraints ihn variable-cell optimization.
It was implemented quite recently, I think

P.
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Paolo Giannozzi, Dept of Physics, University of Udine
via delle Scienze 208, 33100 Udine, Italy
Phone +39-0432-558216, fax +39-0432-558222