[QE-users] Guidance Required for Stiffness Matrix Calculation from Stress and Strain Data

[Mpayami]

Dear Elham,

Hi.
Once I was interested to do such direct calculations, I followed the method outlined in the following link:

https://docs.materialsproject.org/methodology/materials-methodology/elasticity

as well as the notes provided by Prof. Andrea Dal Corso in the DOC folder of Thermo_pw.

Secondly, as Prof. Nicola Marzari suggested in reply to your post, please mention your affiliation in your posts.

Hope that helps.

Besr regards, 


Mahmoud Payami

NSTRI, AEOI
Tehran, Iran
Email: mpayami at aeoi.org.ir
Phone: +98(0)2182066504
------------------------------------

----- Original Message -----
From: Elham Rezaee (elham.rezaee at unb.ca)
Date: 01/09/1402 15:54
To: users at lists.quantum-espresso.org
Subject: [QE-users] Guidance Required for Stiffness Matrix Calculation from Stress and Strain Data


Hi Team,

I am reaching out for some clarification on the procedure for calculating the stiffness matrix. I understand that it involves applying various strains to our crystalline structure and then measuring the corresponding stress matrices, but I am unsure about the details of this process.

My plan is to apply strains in the range of -1% to +1%. The approach, as I understand it, is to begin by adjusting the 'a' parameter in the x-direction by +1%, and then proceed to modify the other cell parameters such as 'ay', and so on. However, I am unclear about how to systematically organize the relationship between each applied strain and the resulting 3x3 stress tensor. This organization is crucial for the accurate assembly of the stiffness matrix.

Additionally, the sequence in which the cell parameters should be deformed is a point of uncertainty for me. A clear and systematic approach is necessary to ensure the correct construction of the stiffness matrix, which is essential for calculating the elastic properties of our material.

I aim to perform these calculations independently to acquire the stiffness matrix, like those found in the Material Project database, to further evaluate the material's elastic properties.

Could you please provide guidance or point me to resources that could help clarify how to properly organize the strain and stress matrices and determine the sequence of cell parameter deformations?

Thanks,
Elham

_______________________________________________
The Quantum ESPRESSO community stands by the Ukrainian
people and expresses its concerns about the devastating
effects that the Russian military offensive has on their
country and on the free and peaceful scientific, cultural,
and economic cooperation amongst peoples
_______________________________________________
Quantum ESPRESSO is supported by MaX (www.max-centre.eu)
users mailing list users at lists.quantum-espresso.org
https://lists.quantum-espresso.org/mailman/listinfo/users

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.quantum-espresso.org/pipermail/users/attachments/20231122/7420924f/attachment.html>