[Pw_forum] A Quastion about stress

[Paolo Giannozzi]

Mahdi Mirnezhad wrote:

> What are the axises in the stress tensor labaled ? 

cartesian: x,y,z

P.
-- 
Paolo Giannozzi, Democritos and University of Udine, Italy

[Pw_forum] A Quastion about stress

[Eduardo Ariel Menendez Proupin]

> How can we exert a shear force?
A short list of readings

Introduction to Solid State Physics, C. Kittel,
Theory of Elasticity,  Landau &Lifshits

For simulation with Quantum ESPRESSO, you define a strain and the code
calculates stress.
You must obtain a relaxed structure (calculation='vc-relax'), then you apply
deformations to the lattice vectors, but relaxing the atom positions
(calculation='relax')

 One simple example of how to deform the lattice vectors is explained in
J. Appl. Phys. 99, 103504 (2006). See also Phys Rev B 1995; 51: 17431.



An explanation on the theory of ab initio stress calculations is  in

Nielsen OH, Richard M. First?Principles Calculation of Stress. Phys
Rev Lett 1983;50: 697,
and more detailed in PRB 32, 3780 (1985)

Good luck
-- 


Eduardo Menendez
Departamento de Fisica
Facultad de Ciencias
Universidad de Chile
Phone: (56)(2)9787439
URL: http://fisica.ciencias.uchile.cl/~emenendez

Let's pray for the 33 trapped miners! Four months to rescue.
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[Pw_forum] A Quastion about stress

[Mahdi Mirnezhad]

Dear all,
I am a new user of esperesso. I want to calculate the stress of a
graphene like structure. What are the axises in the stress tensor
labaled ? How can we exert a shear force?
Thanks for your answers

Mahdi Mirnezad,
Guilan University