[Wien] proper k-points for Nd

[tran at theochem.tuwien.ac.at]

Hi,

If :DIS at the end of the calculation is in the
range 0.006-0.2, then it's huge. Do the calculations
with "-cc 0.0001".

FT

On Thursday 2019-01-17 21:19, Victor Zenou wrote:

>Date: Thu, 17 Jan 2019 21:19:31
>From: Victor Zenou <zanov at post.bgu.ac.il>
>Reply-To: A Mailing list for WIEN2k users <wien at zeus.theochem.tuwien.ac.at>
>To: A Mailing list for WIEN2k users <wien at zeus.theochem.tuwien.ac.at>
>Subject: Re: [Wien] proper k-points for Nd
>
>Dear Lauri
>Thanks for your answer
>I used only energy convergence criteria (10^-4). Still the charge convergence was between 0.006 and 0.2 e.
>The nearest neighbor distance is 6.856 a.u, I used RMT=2.7 a.u., summed to 5.4 which is much lower than 6.856. Usually large RMT is preferred to make the
>calculations as fast as possible. I plan to check a phases in Al-Ti-Nd and I chose RMT equal to 2.3, 2.5 and 2.7 respectively.
>Victor
>
>
>
>‫בתאריך יום ה׳, 17 בינו׳ 2019 ב-11:16 מאת ‪Laurence Marks‬ <‪L-marks at northwestern.edu‬>:‬
>      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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