[Wien] Calculation of Ueff

Mon Mar 27 16:25:33 CEST 2017

"The two calculations converged but with more than 100 iteration (bad convergence)"
==> did you start them from scratch ? Try to run a calculation with the unchanged inputs (regular setting of electron occupation)
        then use the converged potential to run the calculations with changed input files, (I checked some of my old calculations, it never took more than 20-25 cycles)

you also may increase the number of k-points (plane waves) and rerun the calculation with the preconverged charge densities.

Ciao
Gerhard

DEEP THOUGHT in D. Adams; Hitchhikers Guide to the Galaxy:
"I think the problem, to be quite honest with you,
is that you have never actually known what the question is."

====================================
Dr. Gerhard H. Fecher
Institut of Inorganic and Analytical Chemistry
Johannes Gutenberg - University
55099 Mainz
and
Max Planck Institute for Chemical Physics of Solids
01187 Dresden
________________________________________
Von: Wien [wien-bounces at zeus.theochem.tuwien.ac.at] im Auftrag von karima Physique [physique.karima at gmail.com]
Gesendet: Montag, 27. März 2017 15:41
An: A Mailing list for WIEN2k users
Betreff: Re: [Wien] Calculation of Ueff

thank you very much Prof.Laurence Marks for your answer.

2017-03-27 15:33 GMT+02:00 Laurence Marks <L-marks at northwestern.edu<mailto:L-marks at northwestern.edu>>:
Many years ago I did some tests of the method in that paper. I remember  that the value for Ueff one gets does depend a bit upon the parameters used, e.g. RKMAX, RMTs, k-points. This is not really a surprise, and the value of RKMAX 5 in the original paper was probably a compromise for speed; larger RKMAX will localize the electrons more inside the RMTs.

I would suggest that you use parameters representative of what you will use in your +U calculations for the estimation of the +U value.

And, always remember that what you are doing is estimating the value for an approximate correction of the exchange-correlation potential for use in your computational experiments. It is not truly ab-initio, it is a heuristic approach.

On Mon, Mar 27, 2017 at 8:20 AM, karima Physique <physique.karima at gmail.com<mailto:physique.karima at gmail.com>> wrote:
Thank you for your answer,

The two calculations converged but with more than 100 iteration (bad convergence)
 But in the paper presented by G. K. H. Madsen and P. Novak, they used a single point and a value of RKmax = 5,
Can I force the calculation to 1000 Point for example and RKmax = 8.

2017-03-27 8:16 GMT+02:00 Fecher, Gerhard <fecher at uni-mainz.de<mailto:fecher at uni-mainz.de>>:
your calciulataion is not converged with respect to the number of k-points and/or plane waves, is it ?

Ciao
Gerhard

DEEP THOUGHT in D. Adams; Hitchhikers Guide to the Galaxy:
"I think the problem, to be quite honest with you,
is that you have never actually known what the question is."

====================================
Dr. Gerhard H. Fecher
Institut of Inorganic and Analytical Chemistry
Johannes Gutenberg - University
55099 Mainz
and
Max Planck Institute for Chemical Physics of Solids
01187 Dresden
________________________________________
Von: Wien [wien-bounces at zeus.theochem.tuwien.ac.at<mailto:wien-bounces at zeus.theochem.tuwien.ac.at>] im Auftrag von karima Physique [physique.karima at gmail.com<mailto:physique.karima at gmail.com>]
Gesendet: Montag, 27. März 2017 02:09
An: wien at zeus.theochem.tuwien.ac.at<mailto:wien at zeus.theochem.tuwien.ac.at>
Betreff: [Wien] Calculation of Ueff

Dear Wien2k users,

I used the method described by G. K. H. Madsen and P. Novak but I found two different values of Ueff when I changed the number of K-point and RKmax

For K=1 Point and RKmax 5 i found Ueff=3.6 eV
but For K=100 Points and RKmax 8.5 i found Ueff=5.4 eV

Do I use one point only ? otherwise I want to know why I had this difference
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--
Professor Laurence Marks
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