[Pw_forum] problem with pseudopotential

[luch001]

Dear all,
 
I am confused with some questions about the pseudopotential (PP).
 
Above all, my research is mainly on the materials properties under high compression, including the phase transition under pressure. My questions are as following:
 
I want to determine the stable structure by searching the global minimum of the ab initio free energy. Therefore, I should get reliable free energy with acceptable parameters (e.g., k-mesh and Ecut). In other words, the convergence of the PP should be good enough, namely a bit softer PP. But simultaneously I should guarantee the pseudo cores do not overlap too much, that is to say the rc should be small enough. This is paradox. How can I give attentions to the two things mentioned above ? Overlap to what extent is reasonable ?
 
Any reply is appreciated!
 
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