[Wien] Re : need clarification on changes in spin magnetic moment in cell after SCF run
Peter Blaha
pblaha at theochem.tuwien.ac.at
Thu Sep 5 08:02:21 CEST 2013
Ok. This looks as if with increased doping (Si) the moment gets more stable.
In particular in intermediate cases, it seems to be very "subtle" and small
changes in parameters may give quite some effects.
Even if it is expensive, you need to check k-mesh and also RKmax-convergence
(I do not know your RMTs).
You may check with LDA (often GGAs tend to give a more magnetic solution than LDA).
And, when using GGA for these small effects, where lot of the moment may come from
delocalized electrons, you should check with an IFFT factor =4 or 8 (in case.in0)
(may need lapw0_mpi).
And finally: In many cases (but not all: FeAl is FM only in theory !!) LDA/GGA
underestimates localization and thus the formation of local moments, in particular
for impurities ....
Am 04.09.2013 11:27, schrieb venkatesh chandragiri:
>
> 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 forx = 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 specifytight -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 resultsfor 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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--
-----------------------------------------
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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