[Pw_forum] Strain calculation through quantum espresso

[Giovanni Cantele]

Dimpy Sharma wrote:
> Hi Paolo,
>
>  I want to know about calculating strain from Q.E , 
I cannot well understand your question. If I'm not wrong, strain is a 
measure of the deformation of a material,
the stress is the corresponding "load" applied to the material and 
producing the strain. So, if you apply a deformation ("strain") to your 
material,
let's say a cubic material with lattice constant A0 with strain along 
the x direction, you are changing the lattice constant
along x from the equilibrium value A0 to some value A. The strain will 
be measured as (A - A0) / A0.

> howver from stress also we can calculate stress,
?????

> as we can relate stress and strain .
>
>   
The QE calc. will give you the corresponding stress tensor if you set 
tstress=.true., *even though* you are using
calculation='scf', 'relax', ....

stress in QE:
http://www.quantum-espresso.org/wiki/index.php/Methodological_Background#Stress



Giovanni

 

-- 



Dr. Giovanni Cantele
Coherentia CNR-INFM and Dipartimento di Scienze Fisiche
Universita' di Napoli "Federico II"
Complesso Universitario di Monte S. Angelo - Ed. 6
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