Thank you Lucas,
the problem is known:
https://gitlab.com/QEF/q-e/-/issues/148
it onmly needs someone to fix it.
cheers
On 3/12/20 12:48 AM, Lucas Nicolás Lodeiro Moraga wrote:
Hello all!
I am a QE user since 2017, I start using the 5.4 version, and now I am
using the 6.1 version. I saw that when you use the starting pot/wfc
options, there are some cases where these options does not work very
well, and some obvious changes can be done. First of all, I do not know
if these changes are already implemented in the new versions, I
apologize if was done in the new versions.
For GGA calculation there are 4 combinations of starting guess: the
default, a random/atomic wfc and density. The full read guess with wfc
and density. Read density only. This three are ok. The fourth is only
reading the wfc...
When the wfc is the only reading one, the program use the read wfc, and
a random/atomic density. This situation is not useful because the read
wfc does not match with the random density (and with the "random
potential") and there is not any improvement over the calculation. I
think (I do not know if this implementation is easy) for this case the
density must be created using the wfc, because if the wfc is near the
minimum, the density is near the minimum too.
Another case is for hybrid functionals, for the starting wfc and
starting wfc/density cases, I think some changes could be done. The
typical hybrid calculation starts with a GGA calculation. If you use the
read starting guess from another hybrid calculation, this guess is far
away of GGA minimum, but near the hybrid minimum, and the first GGA
calculation breaks the "good guess" to a GGA solution. If in these cases
the first step was the fock matrix calculation, we can get an upgrade,
because the full potential was very similar to those to the read
wfc/density.
Regards!
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Lorenzo Paulatto - Paris
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