[QE-users] (no subject)

[Paolo Giannozzi]

On 13/11/2024 19:09, fatemeh mahmudi wrote:
> 
> ​Hi Dear users
> What the meaning of |dv-scf|^2 in the output file of phonon calculations?

In the self-consistent procedure an input potential Vin produces an 
output potential Vout. The quantity |dv-scf|^2 is, if I understand it 
right, |dv-scf|^2 = \sum_{i=1}^N (Vout(r_i)-Vin(r_i))^2 / N^2
where the sum runs over the points r_i of the real-space grid spanning 
the unit cell. Convergence is declared when |dv-scf|^2 < tr2_ph, the 
latter being a parameter passed in input.

The choice of the potential as self-consistent variable and of the 
related convergence threshold dates back to many years ago. I think it 
is suboptimal and should be revised.

Paolo
-- 
Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche,
Univ. Udine, via delle Scienze 206, 33100 Udine Italy, +39-0432-558216