[Wien] survey results
Peter Blaha
pblaha at theochem.tuwien.ac.at
Fri Jun 28 18:13:47 CEST 2013
The answer is simple: it is a bug.
As listed on the faq page http://www.wien2k.at/reg_user/faq/rkmax.html
the necessary RKmax for Al and O are both 6.5.
Therefore the spheres should be "equal".
These RKmax estimates come from total energy tests of an atom in a
simple box.
For Al, however, the convergence depends a lot on the semicore-treatment
and at first I had obtained a RKmax=4.5 for Al, but later on it was
updated to 6.5.
Unfortunately, setrmt has the Al in both, the 4.5 and 6.5 section and
thus uses "4.5", which will then make the Al sphere smaller than O.
# Li, Al, Si
sub rkm4_5 {
my ($a) = @_ ;
if ( $a == 3 || $a == 13 || $a == 14 ) {
return 1;
Removing a == 13 from the above, should fix the problem.
I'll update the sources.
On 06/28/2013 05:24 PM, Laurence Marks wrote:
> As a follow up, can I request a little more information comparing the
> New and Old setrmt algorithms perhaps in a FAQ. I just noticed a very
> large difference between them for bulk LaAlO3, e.g.
>
> Old:
> atom Z RMT-max RMT
> 1 8.0 1.77 1.77
> 2 13.0 1.77 1.77
> 3 57.0 2.50000 2.50000
>
> New
> atom Z RMT-max RMT
> 1 8.0 1.95 1.95
> 2 13.0 1.60 1.60
> 3 57.0 2.50000 2.50000
>
> I assume that the New algorithm is better and this is "right", but it
> would be helpful to know why O is now being chosen so much larger than
> Al, more like the relative atomic radii
>
>
> On Thu, Jun 27, 2013 at 1:47 PM, Peter Blaha
> <pblaha at theochem.tuwien.ac.at> wrote:
>> I've updated http://www.wien2k.at/reg_user/faq/rkmax.html
>>
>> Maybe it helps if I put a link in w2web in the initialization section next to the
>> RKmax input/editing ? (But which experienced user is using w2web for intialization ?)
>>
>>
>> Am 27.06.2013 16:49, schrieb Stefaan Cottenier:
>>>
>>> One week ago, a two-question survey was posted on this mailing list.
>>> Here comes the result and a discussion/interpretation of the data.
>>>
>>> The goal of the survey was to collect quantitative information on the
>>> following hypothesis:
>>>
>>> "In the transition from code development to code usage, inevitable some awareness and knowledge about fine (?) details gets lost. Developers tend to think that users know
>>> more than they actually do. While users tend to think that there are less hidden subtleties than there actually are. It might well be that grey intermediate area of
>>> supposed/lacking knowledge is far larger than either of both parties thinks it is."
>>>
>>> The discussion of one week ago about the relation between RKmax and Rmt offered an opportunity to collect some data to examine this hypothesis. The topic was one about
>>> which an experienced user could think: "You can't use wien2k properly if you don't know this." While a 'general user' could think: "I can survive without this."
>>>
>>> 34 people filled out the survey. Less than the 100 I hoped for, but nevertheless sufficient for meaningful conclusions. The results can be found for a while at
>>> https://dl.dropboxusercontent.com/u/10829484/Results%20RKmax%20survey.pdf (attachment too large for this list).
>>>
>>> 1/3 of the respondents say they could have given the right answer on the RKmax question themselves. 2/3 say this was new for them. As one can expect that users who have no
>>> clue at all about the topic are less
>>> likely to take part in the survey, it seems fair to conclude that 75% or more of the wien2k community was not aware about this RKmax issue. A
>>> number that might surprise some people.
>>>
>>> Whereas the first question of the survey roughly probes 'understanding', the second question of the survey asked about 'experience' (measured as the amount of years someone
>>> has been using wien2k). Slightly less than one half of the respondents were relatively new users (<3y), the other half were quite to very much experienced (>3y, >7y). It is
>>> interesting to correlate the answers on both questions in a knowledge-vs-experience graph (3th page of
>>> https://dl.dropboxusercontent.com/u/10829484/Results%20RKmax%20survey.pdf ) :
>>>
>>> It is reassuring to observe in this correlation that roughly spoken understanding seems to increase as a function of experience (or time). Nevertheless, even in the
>>> category of the most experienced users (>7y), there are still almost twice as many who were not aware of the RKmax issue than those who were (26% vs. 15%).
>>>
>>> This is only a rough observation, that does not pretend to be a statistically significant scientific study. It does point to a trend, however.
>>>
>>> The bottom line: is there anything all of us, as a community, can do to improve the knowledge transfer towards 'general users'? Feel free to discuss this on this mailing
>>> list, and in particular, to post suggestions.
>>>
>>> Stefaan
>>>
>>>
>>>
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>>
>> --
>> -----------------------------------------
>> Peter Blaha
>> Inst. Materials Chemistry, TU Vienna
>> Getreidemarkt 9, A-1060 Vienna, Austria
>> Tel: +43-1-5880115671
>> Fax: +43-1-5880115698
>> email: pblaha at theochem.tuwien.ac.at
>> -----------------------------------------
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>
>
>
--
P.Blaha
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