[Wien] Re : need clarification on changes in spin magnetic moment in cell after SCF run
Fecher, Gerhard
fecher at uni-mainz.de
Thu Sep 5 09:46:04 CEST 2013
For a single impurity you have a highly symmetric system, but it seems you did not make use of it for unknown reason,
did you check that all resulting quantities fullfill the correct symmetry requirements.
For Example: The impurity Si atom has 8 Fe atoms as nearest neighbours, are the forces and moments on all of these atoms the same ?
(Atom 41 does not tell anything as noone knows what atom that is, and I even don't like to know it).
What about the next shell that contains V and Al atoms, is everything symmetric ?
What is the purpose of youre calculation ? Checking for impurities or calculations for random alloy ?
What is the purpose to do the calculation with a tetragonal cell and P1 symmetry ?
The two most different cases you may have at your impurity concentration of 1/16 by doing the following
a) maximum distance between two Si atoms
use a 2x2x2 cubic cell (should have 128 atoms) based on the regular Hausler cell with Al on 000
replace in the P1 supercell the Al on 000 and 1/2 1/2 1/2 by Si
use the symmetry that is found during initialisation (should be clearly higher than P1)
you may also wish to reorder the atoms positions in the cell to see better what are the nearest, next nearest etc. neighbors with same distances to the Si.
b) minimum distance between two Si atoms
principally the same as a) but put the second Si on the Al position closest to 0, 0, 0
this will be a dimere impurity.
Thats for example if you like to check whether dimer impurities are more stable than monomers.
If you like to know something about a random alloy, where it is not clear at what posiotions the Si atoms are, then you have to do the same
also for all other cases between a) and b) . In complicated cases you may need to do the same procedure for 3x3x3 supercells.
Finally you have to average over all non-equivalent cases.
!!!! The numbers you find for a single case will not have any meaning but only the average !!!!
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
________________________________________
Von: wien-bounces at zeus.theochem.tuwien.ac.at [wien-bounces at zeus.theochem.tuwien.ac.at]" im Auftrag von "venkatesh chandragiri [venkyphysicsiitm at gmail.com]
Gesendet: Mittwoch, 4. September 2013 11:27
An: wien at zeus.theochem.tuwien.ac.at
Betreff: [Wien] Re : need clarification on changes in spin magnetic moment in cell after SCF run
Dear Blaha sir,
Please, excuse me for the delayed reply. In the below, i have given the answers for your comments
a) The first thing: Which magnetic state do you get for the normal Fe2VAl compound (in the "normal" small unit cell) ???
Answer :
For normal Fe2VAl compound, the calculations shows the non magnetic ground state with zero total magnetic moment.
b) Even when Fe2VAl turns out to be nonmagnetic ???, by doping with Si, you introduce an extra electron into the system and thus you could get some magnetism, maybe even some "strange one", although your numbers did not look very convincing and since you sent several series of MMI values, it is not really clear what one should say.
Answer:
Yes sir, introduction of Si into the Al-site may results some magnetic nature of the doped system. To notice this, i have done calculations for different doping levels of Si and the total magnetic moments are given as fallows.
Mtotal(ub/f.u)
1.5E-5 for x =0 (Fe2VAl)
-0.0348 for x = 0.065 (This was the alloy under present discussion)
-1.2038E-4 for x = 0.125
0.10999 for x =0.25
0.34886 for x = 0.5
0.85612 for x = 1 (Fe2VSi)
c)grep :MMI00x case.scf must be really "stable".
Answer:
i have seen the convergence for the 41th atom for x = 0.0625 alloy, the moments are well converged up to third decimal point. kindly, see the below details.
:MMI041: MAGNETIC MOMENT IN SPHERE 41 = 1.00142
:MMI041: MAGNETIC MOMENT IN SPHERE 41 = 0.98544
:MMI041: MAGNETIC MOMENT IN SPHERE 41 = 0.90941
:MMI041: MAGNETIC MOMENT IN SPHERE 41 = 0.87627
:MMI041: MAGNETIC MOMENT IN SPHERE 41 = 0.52277
:MMI041: MAGNETIC MOMENT IN SPHERE 41 = 0.37124
:MMI041: MAGNETIC MOMENT IN SPHERE 41 = 0.08345
:MMI041: MAGNETIC MOMENT IN SPHERE 41 = -0.06480
:MMI041: MAGNETIC MOMENT IN SPHERE 41 = -0.11310
:MMI041: MAGNETIC MOMENT IN SPHERE 41 = -0.10418
:MMI041: MAGNETIC MOMENT IN SPHERE 41 = -0.15170
:MMI041: MAGNETIC MOMENT IN SPHERE 41 = -0.19035
:MMI041: MAGNETIC MOMENT IN SPHERE 41 = -0.19300
:MMI041: MAGNETIC MOMENT IN SPHERE 41 = -0.17201
:MMI041: MAGNETIC MOMENT IN SPHERE 41 = -0.20097
:MMI041: MAGNETIC MOMENT IN SPHERE 41 = -0.24794
:MMI041: MAGNETIC MOMENT IN SPHERE 41 = -0.27963
:MMI041: MAGNETIC MOMENT IN SPHERE 41 = -0.28508
:MMI041: MAGNETIC MOMENT IN SPHERE 41 = -0.29251
:MMI041: MAGNETIC MOMENT IN SPHERE 41 = -0.31931
:MMI041: MAGNETIC MOMENT IN SPHERE 41 = -0.33522
:MMI041: MAGNETIC MOMENT IN SPHERE 41 = -0.33897
:MMI041: MAGNETIC MOMENT IN SPHERE 41 = -0.35567
:MMI041: MAGNETIC MOMENT IN SPHERE 41 = -0.32782
:MMI041: MAGNETIC MOMENT IN SPHERE 41 = -0.32364
:MMI041: MAGNETIC MOMENT IN SPHERE 41 = -0.31298
:MMI041: MAGNETIC MOMENT IN SPHERE 41 = -0.28405
:MMI041: MAGNETIC MOMENT IN SPHERE 41 = -0.26110
:MMI041: MAGNETIC MOMENT IN SPHERE 41 = -0.18485
:MMI041: MAGNETIC MOMENT IN SPHERE 41 = -0.17598
:MMI041: MAGNETIC MOMENT IN SPHERE 41 = -0.14717
:MMI041: MAGNETIC MOMENT IN SPHERE 41 = -0.13809
:MMI041: MAGNETIC MOMENT IN SPHERE 41 = -0.12733
:MMI041: MAGNETIC MOMENT IN SPHERE 41 = -0.12009
:MMI041: MAGNETIC MOMENT IN SPHERE 41 = -0.11444
:MMI041: MAGNETIC MOMENT IN SPHERE 41 = -0.08895
:MMI041: MAGNETIC MOMENT IN SPHERE 41 = -0.09288
:MMI041: MAGNETIC MOMENT IN SPHERE 41 = -0.07238
:MMI041: MAGNETIC MOMENT IN SPHERE 41 = -0.07069
:MMI041: MAGNETIC MOMENT IN SPHERE 41 = -0.06820
:MMI041: MAGNETIC MOMENT IN SPHERE 41 = -0.06445
:MMI041: MAGNETIC MOMENT IN SPHERE 41 = -0.06526
:MMI041: MAGNETIC MOMENT IN SPHERE 41 = -0.05900
:MMI041: MAGNETIC MOMENT IN SPHERE 41 = -0.05959
:MMI041: MAGNETIC MOMENT IN SPHERE 41 = -0.05841
:MMI041: MAGNETIC MOMENT IN SPHERE 41 = -0.05780
:MMI041: MAGNETIC MOMENT IN SPHERE 41 = -0.05715
:MMI041: MAGNETIC MOMENT IN SPHERE 41 = -0.05646
:MMI041: MAGNETIC MOMENT IN SPHERE 41 = -0.05631
:MMI041: MAGNETIC MOMENT IN SPHERE 41 = -0.05587
:MMI041: MAGNETIC MOMENT IN SPHERE 41 = -0.05587
:MMI041: MAGNETIC MOMENT IN SPHERE 41 = -0.05571
:MMI041: MAGNETIC MOMENT IN SPHERE 41 = -0.05564
:MMI041: MAGNETIC MOMENT IN SPHERE 41 = -0.05545
:MMI041: MAGNETIC MOMENT IN SPHERE 41 = -0.05526
:MMI041: MAGNETIC MOMENT IN SPHERE 41 = -0.05536
:MMI041: MAGNETIC MOMENT IN SPHERE 41 = -0.05544
:MMI041: MAGNETIC MOMENT IN SPHERE 41 = -0.05553
:MMI041: MAGNETIC MOMENT IN SPHERE 41 = -0.05564
:MMI041: MAGNETIC MOMENT IN SPHERE 41 = -0.05566
:MMI041: MAGNETIC MOMENT IN SPHERE 41 = -0.05572
:MMI041: MAGNETIC MOMENT IN SPHERE 41 = -0.05592
:MMI041: MAGNETIC MOMENT IN SPHERE 41 = -0.05602
:MMI041: MAGNETIC MOMENT IN SPHERE 41 = -0.05624
:MMI041: MAGNETIC MOMENT IN SPHERE 41 = -0.05641
:MMI041: MAGNETIC MOMENT IN SPHERE 41 = -0.05651
:MMI041: MAGNETIC MOMENT IN SPHERE 41 = -0.05660
:MMI041: MAGNETIC MOMENT IN SPHERE 41 = -0.05668
:MMI041: MAGNETIC MOMENT IN SPHERE 41 = -0.05673
:MMI041: MAGNETIC MOMENT IN SPHERE 41 = -0.05678
:MMI041: MAGNETIC MOMENT IN SPHERE 41 = -0.05688
:MMI041: MAGNETIC MOMENT IN SPHERE 41 = -0.05689
:MMI041: MAGNETIC MOMENT IN SPHERE 41 = -0.05705
:MMI041: MAGNETIC MOMENT IN SPHERE 41 = -0.05709
:MMI041: MAGNETIC MOMENT IN SPHERE 41 = -0.05712
:MMI041: MAGNETIC MOMENT IN SPHERE 41 = -0.05715
:MMI041: MAGNETIC MOMENT IN SPHERE 41 = -0.05721
:MMI041: MAGNETIC MOMENT IN SPHERE 41 = -0.05720
:MMI041: MAGNETIC MOMENT IN SPHERE 41 = -0.05730
:MMI041: MAGNETIC MOMENT IN SPHERE 41 = -0.05732
:MMI041: MAGNETIC MOMENT IN SPHERE 41 = -0.05738
:MMI041: MAGNETIC MOMENT IN SPHERE 41 = -0.05740
d) You have to specify tight -ec -cc parameters. And k-mesh, RKmax ... ?
Answer:
grep :ENE case.scf results for x = 0.0625 alloy
:ENE : ********** TOTAL ENERGY IN Ry = -119704.65580633
:ENE : ********** TOTAL ENERGY IN Ry = -119704.65580848
:ENE : ********** TOTAL ENERGY IN Ry = -119704.65580933
:ENE : ********** TOTAL ENERGY IN Ry = -119704.65580986
:ENE : ********** TOTAL ENERGY IN Ry = -119704.65581011
:ENE : ********** TOTAL ENERGY IN Ry = -119704.65581074
:ENE : ********** TOTAL ENERGY IN Ry = -119704.65581036
:ENE : ********** TOTAL ENERGY IN Ry = -119704.65581087
:ENE : ********** TOTAL ENERGY IN Ry = -119704.65581059
:ENE : ********** TOTAL ENERGY IN Ry = -119704.65580990
grep :DIS case.scf results for x = 0.0625 alloy
:DIS : CHARGE DISTANCE ( 0.0003705 for atom 15 spin 2) 0.0002212
:DIS : CHARGE DISTANCE ( 0.0001581 for atom 15 spin 1) 0.0000896
:DIS : CHARGE DISTANCE ( 0.0001557 for atom 15 spin 2) 0.0000830
:DIS : CHARGE DISTANCE ( 0.0001729 for atom 21 spin 2) 0.0000793
:DIS : CHARGE DISTANCE ( 0.0001464 for atom 21 spin 1) 0.0000847
:DIS : CHARGE DISTANCE ( 0.0001740 for atom 11 spin 2) 0.0000898
:DIS : CHARGE DISTANCE ( 0.0001994 for atom 26 spin 2) 0.0001041
:DIS : CHARGE DISTANCE ( 0.0001006 for atom 30 spin 1) 0.0000607
:DIS : CHARGE DISTANCE ( 0.0001967 for atom 14 spin 2) 0.0000709
:DIS : CHARGE DISTANCE ( 0.0000968 for atom 31 spin 2) 0.0000502
RKmax is 7
K-mesh is 2x2x5
e) Structure optimization ? -fc 1.0 ; check forces and relaxe the atoms
around Si.
Answer:
Yes sir, before attempting the SCF calculations, this structure is well optimized for
the minimum energy volume and the obtained min volume structure is again
optimized for minimum forces by keeping -fc is 2 mRy/bhor and we got 1.6 mRy/bohr maximum force
among all the individual atoms after the force minimization.
Then after using this force minimized file, we did SCF calculations which results
total moment of -0.090492 ub.
Looking forward to your comments on the above replies....
regards,
venkatesh.
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