[Wien] Convergence problem
tran at theochem.tuwien.ac.at
tran at theochem.tuwien.ac.at
Tue Dec 30 10:52:30 CET 2014
Hi,
The struct file that I used is attached. For my purpose, the size of
the unit cell was large enough to avoid spurious interactions between
neighbouring cells. Note that a, b and c are different in order to avoid
to high symmetry.
F. Tran
On Mon, 29 Dec 2014, Muhammad Sajjad wrote:
> Dear Prof. Marks and F. TranThank you so much for your helpful suggestions. I was already doing the spin polarization calculations. I have got the convergence
> by using
> mixing factor 0.1, starting calculation with PRATT and then switched to MSR1 after 7 cycles, and the command runsp_lapw -cc 0.00001 -in1ef -i 150
> The obtained magnetic moment was 2.00009.
>
> Dear Tran I would really appreciate if you share some more details about case.struct file. It will definitely be helpful for me as well as for others.
>
> Kind Regards
> Dr. Sajjad
>
> On Mon, Dec 29, 2014 at 3:50 AM, <tran at theochem.tuwien.ac.at> wrote:
> The calculation for an isolated atom with a code which uses periodic
> boundary conditions (like WIEN2k) is not trivial. This is what I have done
> recently for most atoms of the periodic table (excluding f-systems), and
> for some of the transition-metal atoms this was extremely difficult to
> achieve convergence.
>
> A few hints (that I used):
>
> 1) It is important (and necessary depending on the atom) to reduce the
> symmetry from cubic to, e.g., orthorhombic to be able to access the
> electronic configuration with the lowest energy (this is the procedure
> followed by several research groups like VASP for instance).
> If necessary I can give more details about the case.struct that I used.
>
> 2) lapw0 requires a lot of memory, while lapw1 requires both
> memory and time. To reduce computer time for lapw1, I was using
> iterative digonalization (this was my command for all atoms):
> runsp_lapw -ec 0.0001 -cc 0.0001 -it -i 1000 -NI
>
> 3) For the Ni atom the magnetic moment should be 2:
> :MMTOT: SPIN MAGNETIC MOMENT IN CELL = 2.00238
>
> 4) I was using the default setting for mixer.
>
> F. Tran
>
> On Sun, 28 Dec 2014, Laurence Marks wrote:
>
>
> Also, only 1 k-point (Gamma), an RMT and RKMax similar to what you use for
> bulk Ni, particularly as I assume you are doing the calculation to get an
> enthalpy of formation. You may have to use the mpi versions as it is
> probably too large for a non-mpi run.
>
> If you are doing WC+U (or -ineece) the U (or on-site hybrid) removes the
> phase transition so convergence should be simple.
>
> Straight WC is not a simple calculation because the physics for an isolated
> Ni atom is wrong. With wrong physics there is in fact no guarantee that the
> calculation will ever converge!
>
> ___________________________
> Professor Laurence Marks
> Department of Materials Science and Engineering
> Northwestern University
> www.numis.northwestern.edu
> MURI4D.numis.northwestern.edu
> Co-Editor, Acta Cryst A
> "Research is to see what everybody else has seen, and to think what nobody
> else has thought"
> Albert Szent-Gyorgi
>
> On Dec 28, 2014 11:47 AM, "Laurence Marks" <L-marks at northwestern.edu> wrote:
>
> You almost certainly need to run spin polarized, probably MSR1
> (GREED 0.1), TEMPS (room temp). The convergence is complicated
> for WC (& simple GGAs) due to an electronic phase transition
> between sp & d occupation near the fixed point.
>
> ___________________________
> Professor Laurence Marks
> Department of Materials Science and Engineering
> Northwestern University
> www.numis.northwestern.edu
> MURI4D.numis.northwestern.edu
> Co-Editor, Acta Cryst A
> "Research is to see what everybody else has seen, and to think
> what nobody else has thought"
> Albert Szent-Gyorgi
>
> On Dec 28, 2014 10:47 AM, "Muhammad Sajjad" <sajjadpu at gmail.com>
> wrote:
> Dear Users I am running SCF calculation for Ni with
> lattice constant of 30 Bohr and using WC-GGA. The
> calculation is not converging even upto 100
> iterations and more. To solve the problem I have
> performed following steps
>
> switched to TEMPS = 0.005 from TETRA
> Changed MSR1 to PRATT
> changed mixing factor (increase and decrease from 0.2)
>
> Thanking in advance.
>
> Dr. Sajjad
>
>
>
> _______________________________________________
> Wien mailing list
> Wien at zeus.theochem.tuwien.ac.at
> http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
> SEARCH the MAILING-LIST at: http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html
>
>
>
>
-------------- next part --------------
Ni
P LATTICE,NONEQUIV.ATOMS: 1
MODE OF CALC=RELA unit=ang
18.897269 18.991755 19.086241 90.000000 90.000000 90.000000
ATOM -1: X=0.00000000 Y=0.00000000 Z=0.00000000
MULT= 1 ISPLIT= 8
Ni NPT= 781 R0=0.00005000 RMT= 1.8000 Z: 28.0
LOCAL ROT MATRIX: 1.0000000 0.0000000 0.0000000
0.0000000 1.0000000 0.0000000
0.0000000 0.0000000 1.0000000
8 NUMBER OF SYMMETRY OPERATIONS
-1 0 0 0.00000000
0-1 0 0.00000000
0 0-1 0.00000000
1
-1 0 0 0.00000000
0-1 0 0.00000000
0 0 1 0.00000000
2
-1 0 0 0.00000000
0 1 0 0.00000000
0 0-1 0.00000000
3
-1 0 0 0.00000000
0 1 0 0.00000000
0 0 1 0.00000000
4
1 0 0 0.00000000
0-1 0 0.00000000
0 0-1 0.00000000
5
1 0 0 0.00000000
0-1 0 0.00000000
0 0 1 0.00000000
6
1 0 0 0.00000000
0 1 0 0.00000000
0 0-1 0.00000000
7
1 0 0 0.00000000
0 1 0 0.00000000
0 0 1 0.00000000
8
More information about the Wien
mailing list