[Pw_forum] problem releated to calculating elastic constants

Hande Ustunel hande at newton.physics.metu.edu.tr
Fri Aug 8 12:57:24 CEST 2008

Dear Premlata,

It's normal for LDA to underestimate the lattice but in your case the error
is about 4%. I would start to get nervous. One usually aims at 1 or at most
2 percent. I suggest you try other pseudopotentials and/or try to make sure
that you are getting good fits for your Ecut, Nk, smearing (if necessary)
parameters. By a "good curve" I mean one which is not too bumpy.


On Fri, 8 Aug 2008, premlata pandit wrote:

> hello
>  the experimental lattice constant of Li2S is 10.7867 a.u.
> and my calculated equlibrium lattice constant is 10.375 a.u. by using  LDA
> pseudopotential in pwscf calculation.
> can i use this lattice canstant to calculating  elastic constants?

Hande Toffoli
Department of Physics
Office 439
Middle East Technical University
Ankara 06531, Turkey
Tel : +90 312 210 3264

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