[Pw_forum] pressure from pw calculation-further

[Stefano de Gironcoli]

W. YU wrote:

>
>By the way, where can I find the literature explain
>this "Pulay stress". I didn't find it in the mannual 
>or the input pw.
>
>best regards!
>
>  
>
The problem you are meeting is and old and well known one.
A detailed and clear discussion of what happens can be found in
P.GomesDacosta, O.H. Nielsen, and K. Kunc,
"Stress theorem in the determination of static equilibrium by
the density functional method"
J.Phys.C:SolidStatePhys 19, 3163-3172 (1986). 

Possible "solutions" has been proposed by many authors and one
which is implemented in the ESPRSSO codes is described in
M.Bernasconi, GL Chiarotti, P. Focher, S. Scandolo, E. Tosatti, and M. 
Parrinello,
"First-Principle Constant-Pressure Molecular-Dynamics"
J. Phys. Chem. Solids  56,  501-505  (1995).

Relevand input variables in the PWscf, FPMD and CP codes are: ecfixed, 
qcutz, q2sigma

best regards,

Stefano de Gironcoli