[QE-users] negative phonons in LiC6 when switching to GGA pps

[Михаил Петров]

Hello,

I am calculating phonons for monolayer LiC6. When I use LDA pseudopotentials I get the correct result but when I switch to GGA I get a negative phonon branch at the high symmetry point M (hexagonal lattice) and its vicinity. I anticipated different behaviour around the Gamma point but everything else normally shouldn't be very different. Is there some specific set of variables that one should add when using GGA pps?

Another thing, I didn't redo the convergence studies but the parameters I use should be an overkill. I calculated phonons for this material with GGA pps in ABINIT with parameters even less than I used now and there it was all positive. 

Best regards, Mikhail   


-- 
Михаил Петров
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.quantum-espresso.org/pipermail/users/attachments/20190520/cb51f4fd/attachment.html>