Dear Zhao Yuan
I would never contradict Nicola :-)
But I would add a very practical criterion for beginners: take the Fe
unit cell and progressively increase the automatic sampling of k
points, i.e. 2 2 2, 4 4 4, 8 8 8, ... You will see that as the
sampling of the Brillouin zone increases, some quantities (generally)
start to converge: eigenvalues, total energy, stress, ... Depending on
what you want to know with your simulations, you decide that a given
k-points mesh satisfies your purpose. Remember that in principle you
should do the same thing in the case of wavefunction/density cutoffs...
HTH
Giuseppe
Nicola Marzari <[email protected]> ha scritto:
Dear Zhao Yuan,
On 13/12/2018 14:42, Zhao Yuan Leong wrote:
1. Is it normally better to define k-points manually or to do it
automatically? If its manually, how does one normally determine
which points to take in k-space?
A safe starting point is to have for each crstallographic directions
a density corresponding to 0.15 1/Å, using 0.02 Ry of cold smearing.
You might need a higher density/more k-points, in rare cases, and
often less - you should test carefully if mission critical - see
here for an overview:
http://theossrv1.epfl.ch/Main/ElectronicTemperature
2. Regarding the DOS/band calculations, how does one normally
determine the pathway in reciprocal space for the DOS calculations?
I've read that these are along the high symmetry points - if so,
how do I determine them and do I get them from the literature or
some crystallography database. Would on then write a script to
interpolate along these points?
Thanks to Giovanni Pizzi and co., this problem is fully solved. Just
use this: https://www.materialscloud.org/work/tools/seekpath
nicola
--
----------------------------------------------------------------------
Prof Nicola Marzari, Chair of Theory and Simulation of Materials, EPFL
Director, National Centre for Competence in Research NCCR MARVEL, EPFL
http://theossrv1.epfl.ch/Main/Contact http://nccr-marvel.ch/en/project
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GIUSEPPE MATTIOLI
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