[Wien] proper k-points for Nd

[Laurence Marks]

With such large RMT you certainly need HDLO for Nd, perhaps both d & f. I
would not want to use such large RMTs.

Have you checked that the charge convergence is good?

_____
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

On Thu, Jan 17, 2019, 03:04 Victor Zenou <zanov at post.bgu.ac.il wrote:

> Hi
> Here is updated question:
>
> Dear Wien2k users
>
> I'm using wien2k version 17.1 installed on Ubunto 18.04.
>
> I need to calculate the enthalpy of formation of few intermetallic phases
> that include Nd. For that element I used RMT=2.7 a.u. and RMT*Kmax=8.5
> for spin-polarization calculations via GGA-PBE. I didn't try spin-orbit
> coupling. Yet.
>
> The first stage is to choose proper k-points, which will give accurate
> results (I used 1x10^-4 Ryd for energy convergence) on one hand, but on the
> other hand won't be expensive in terms of computing time.
>
> I noticed that there are large energy fluctuations (1x10^-2 Ryd; which
> are 2 order of magnitude higher than the energy accuracy (defined by
> convergence criterion), even when I went to 15,000 k-points. Here is a list
> of energy as function of k-points:
>
> K-points          IBZ      E [Ryd]
>
>  100       8        -77040.4692
>
>  500     38        -77040.4780
>
> 1000    81        -77040.5062
>
> 2000    120      -77040.5061
>
> 3000    208      -77040.4391
>
> 4000    244      -77040.4699
>
> 5000    280      -77040.4878
>
> 7500    455      -77040.4707
>
> 10000  540      -77040.4881
>
> 15000  840      -77040.4694
>
>
>
> I would be happy to get an idea what could have gone wrong.
>
> Best regards, Victor
>
>
> ‫בתאריך יום ד׳, 16 בינו׳ 2019 ב-13:59 מאת ‪Victor Zenou‬‏ <‪
> zanov at post.bgu.ac.il‬‏>:‬
>
>> Dear Wien2k users
>>
>> I'm using wien2k version 17.1 installed on Ubunto 18.04.
>>
>> As a part of investigation of intermetallic phases in Al-Ti-Nd system, I
>> need to calculate the enthalpy of formation of few phases in that system.
>> For that purpose, I start calculating enthalpy (equal to energy at 0K) for
>> each element and phase at their optimal relaxed state.  I used
>> spin-polarization calculations. (GGA-PBE) As advised in Wien2k website I
>> used the same RMT for each elements: 2.3, 2.5 and 2.7 a.u. for Al, Ti and
>> Nd, respectively. Also proper RMT*Kmax (7.5 to Ti, 8.5 to Nd and 7.0 for
>> the rest).
>>
>> The first stage is to choose proper k-points, which give you accurate
>> results (I used 1x10^-4 Ryd for energy convergence) on one hand, but also
>> some save computing time.
>>
>> The calculation for all elements and phases went OK, but Nd. From certain
>> k-points the energy fluctuated between 2 values (differed by 1x10^-2).
>> Attach a list of energy as function of k-points:
>>
>> K-points          IBZ      E [Ryd]
>>
>>  100       8        -77040.4692
>>
>>  500     38        -77040.4780
>>
>> 1000    81        -77040.5062
>>
>> 2000    120      -77040.5061
>>
>> 3000    208      -77040.4391
>>
>> 4000    244      -77040.4699
>>
>> 5000    280      -77040.4878
>>
>> 7500    455      -77040.4707
>>
>> 10000  540      -77040.4881
>>
>> 15000  840      -77040.4694
>>
>>
>>
>> I tried to get smart and did volume optimization using 4000 k-points,
>> later 5000 k-points. I got strange results.
>>
>> I would be happy to get an idea what could have gone wrong.
>>
>> I didn't try spin-orbit coupling
>>
>> Best regards, Victor
>>
>>
>>
>>
>>
>
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