[Pw_forum] phonon instability

Dear Prof. Baroni: Thank you very much for your reply. However, what I wanted to say is, although QE doesn't support frozen-ph as a "function", it can still be calculated through certain steps. Just as elastic constant calculation, we can calculate in any DFT code, but only several code provide

[Pw_forum] phonon instability

As I know, frozen phonon method is not implemented in QE. You can use frozen-ph method either by the free software "phon", http://www.homepages.ucl.ac.uk/~ucfbdxa/, or make it manually like this tutorial: http://www.abinit.org/documentation/helpfiles/for-v6.8/tutorial/lesson_rf1.html, even tho

[Pw_forum] phonon instability

i am doing the linear response calculation so how can i do frozen phonon calculation On Wed, Aug 24, 2011 at 10:54 PM, Mike Mehl wrote: > To keep from boring everyone, I'm taking this off-line. If anyone else > wants to participate in the discussion please let me know and I'll add > you to the

[Pw_forum] phonon instability

ok but i have seen many papers that this B2 unstability due to some anaharmonic contributions or it may be due to band closing phenomenon can u explain this more correctly because i am doing calculation on transition metal carbides On Wed, Aug 24, 2011 at 9:01 PM, Mike Mehl wrote: > ZnS, WC, and N

[Pw_forum] phonon instability

On Aug 24, 2011, at 8:21 PM, GAO Zhe wrote: > As I know, frozen phonon method is not implemented in QE. ??? *ANY* code able to perform total-energy and atomic-force calculations can be used to do frozen phonons ... SB --- Stefano Baroni - SISSA & DEMOCRITOS National Simulation Center - Tri

[Pw_forum] phonon instability

no i have calculated correctly because the convergence is good with higher k points second is that i have tested zns,wc,NiAs phase none of them have less enthalpy at 130 gpa other thing is that it is stable at above 250 gpa On Wed, Aug 24, 2011 at 7:38 PM, Mike Mehl wrote: > If the B1 structure

[Pw_forum] phonon instability

To keep from boring everyone, I'm taking this off-line. If anyone else wants to participate in the discussion please let me know and I'll add you to the conversation. On 08/24/2011 01:07 PM, bhabya sahoo wrote: > ok but i have seen many papers that this B2 unstability due to some > anaharmonic

[Pw_forum] phonon instability

ZnS, WC, and NiAs are the likeliest candidates, but not the only ones. The unstable B1 phonons lead to structures which relax to something lower in energy than B1. Since all of your candidate structures have a higher enthalpy than B1 at 130 GPa, it can't be one of those structures. Hence, it

[Pw_forum] phonon instability

If the B1 structure is unstable with respect to the B2 structure above 130 GPa, but the B2 structure is dynamically unstable at and above 130 GPa, there are two possible conclusions: 1) The phonons for the B2 structure were not calculated accurately, or 2) There is a competing structure that is

[Pw_forum] phonon instability

sir i am calculating the phase transition of some carbides the transition from B1 to B2 transition occures at 130 gpa by enthalpy compparison but i am able to find phonon instability at 130 gpa for B1 structure but at the same time i am not able to find the dyanamic stability of B2 phase but it occ

[Pw_forum] phonon instability

On Aug 23, 2011, at 8:40 PM, bhabya sahoo wrote: > sir ??? > i am calculating the phase transition of some carbides > the transition from B1 to B2 transition occures at 130 gpa by enthalpy > compparison OK > but i am able to find phonon instability at 130 gpa for B1 structure you mean, a p