I think what Grimvall is saying is that there has been no rigorous
discussion before, but in their review they make this discussion, and
show how the stability condition for phonons does not need any
correction - the material collapses at the pressure where the phonon
dispersions calculated at the corresponding volume go negative. Anyhow,
they cite a few papers and their follow-up corrections.
nic
On 11/01/2021 11:04, Uri Argaman wrote:
Hi all
In the literature the mechanical stability condition using elastic
constants includes explicitly the pressure:
In cubic symmetry, for example:
C11 + 2*C12 +P>0;
C44 +P>0;
C11 + C12 + 2*P>0;
from: Grimvall et al. REVIEWS OF MODERN PHYSICS, VOLUME 84, 2012
In this paper, they write: " There seems to be no rigorous discussion
of this point in papers that have presented ab initio calculations of
phonon dispersion curves under pressure,..."
The stability condition from phonons: omega>0 for all modes. It seems
that it is not equivalent, because the phonon condition is at
constant volume. Is it known what is the condition at constant pressure?
Than you very much
Uri Argaman
Ben-Gurion University of the Negev
Israel
_______________________________________________
Quantum ESPRESSO is supported by MaX (www.max-centre.eu)
users mailing list users@lists.quantum-espresso.org
https://lists.quantum-espresso.org/mailman/listinfo/users
_______________________________________________
Quantum ESPRESSO is supported by MaX (www.max-centre.eu)
users mailing list users@lists.quantum-espresso.org
https://lists.quantum-espresso.org/mailman/listinfo/users
