[Pw_forum] guidance request

[Hadi Arefi]

From: pw_forum-bounces at pwscf.org [mailto:pw_forum-bounces at pwscf.org] On Behalf Of ehsan targholi
Sent: 01 November 2013 09:34
To: pw_forum at pwscf.org
Subject: [Pw_forum] guidance request

hi
dear all, i  am  a graduate student, i have three question about  quantum espresso .

1-     i want to optimize both cell parameter and atomic positions . how  can i do it?

Calculation = “vc-relax” ==> variable cell and atomic position relaxation


2-     dose relax calculation have scf calculation? or we have to run a scf calculation after relax calculation & before nscf calculation? another word Which one is correct ؟ (Relax→scf → nscf → dos)  or  (Relax → nscf → dos)
Relaxation process is several scf calculations until you met the convergence criteria for atomic forces. If you use the same parameters as relax input for your scf calculation (obviously with relaxed coordinates) it should be the same.


3-     if run the scf calculation with one k-point & the nscf calculation with another k-point , my calculation is true or incorrect ?

You may need to look at some online texts for the concept of  scf and nscf (DOS) calculation. Your question is not correct in this way. Normally people use denser k-mesh compare to scf calculation for doing DOS calculation.
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