[Wien] Wien post from pascal.boulet at univ-amu.fr (Errors with DGEMM and hybrid calculations)

[Tran, Fabien]

That's difficult since it may depend on the system, RMT, property, and required accuracy, but roughly (concerning  the parameters in case.inhf):

-For geometry: none of the parameters really need to be increased compared to default. In particular, nband can be set to minimum required (number of occupied bands plus one). Maybe gmax (from case.inhf) should be tested if RMT are chosen clearly smaller than default. The option "-nonself" could also be used for non-magnetic systems.

-For cohesive energy: preferably test nband, gmax, lmaxe and lmaxv. Especially the latter two for systems with an open  f-shell.

-For electronic structure: test lmaxe and lmaxv for systems with an open  f-shell. For the band gap of non-magnetic systems, the option "-diaghf" (https://doi.org/10.1016/j.physleta.2012.01.022) can be used to reduce the computational time by two orders of magnitude.

-For electron density (e.g., for EFG): Test carefully all parameters.

-k-mesh: In general, the convergence of properties with HF/hybrids is slower than with LDA/GGA/MGGA (fortunately only slightly slower with screened hybrids like HSE06).

-RKmax: the convergence is the same as for LDA/GGA/MGGA.

-Computational time: strongly influenced by k-mesh, RKmax, nband, lmaxe and lmaxv. Less by gmax (from case.inhf).


From: Wien <wien-bounces at zeus.theochem.tuwien.ac.at> on behalf of Laurence Marks <laurence.marks at gmail.com>
Sent: Saturday, August 15, 2020 2:40 PM
To: A Mailing list for WIEN2k users
Subject: Re: [Wien] Wien post from pascal.boulet at univ-amu.fr (Errors with DGEMM and hybrid calculations)
  
It would be good to have a brief summary of what matters with hf:
a) For speed
b) For accuracy

It is probably somewhere in the docu, but another cite for the list would be useful (to me as well as others).
_____
Professor Laurence Marks
"Research is to see what everybody else has seen, and to think what nobody else has thought", Albert Szent-Gyorgi
www.numis.northwestern.edu