Dear Ajit,
it's a completely different story - QE uses plane waves as a basis
set, and you just increase the cutoff to improve your basis convergence.
Other codes (quantum chemistry codes, SIESTA...) use atomic-like or
gaussian-like localized basis sets; you need much fewer of these, but
convergence is much trickier.
You probably need to study a good book on electronic structure methods,
and/or some of the tutorials on the QE webpage, before doing much else.
nicola
On 09/01/2014 05:23, Ajit Vallabhaneni wrote:
> Dear QE users,
>
> I am new to QE and am trying to do some calculations on GNRs. In
> the literature i reviewed, it was mentioned that "double numerical atomic
> orbitals along with polarisation functions" were used as a basis for the tens
> of atoms in the unitcell. From the little i understood, the double radial
> functions lead to better accuracy and convergence. I was wondering if it is
> implemented by default in QE or not. Please let me know.
>
>
--
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Prof Nicola Marzari, Chair of Theory and Simulation of Materials, EPFL
