[Wien] Reg: Fixed spin moment calculations

[Peram sreenivasa reddy]

Dear Peter Blaha Sir,

Thank you very much for your replay.

For my system there is no experimental or theoretical proof as it is a
magnet. But in my calculations i got minimum energy in magnetic case with
magnetic moment 1.95 bohr magneton.

I want to confirm that this magnetic moment is correct or not. For that i
am using the fsm calculations.

I followed the step 2 procedure and i got the results like as bellow.

Magnetic moment (bohr magneton)   Energy (Ry)
0.0    -16590.18461593
0.5    -16590.18612148
1.0    -16590.18900235
1.5    -16590.19082779
1.9    -16590.19142097
1.95    -16590.19142434
2.0    -16590.19141282
2.05    -16590.19138454
2.10    -16590.19133936
2.5    -16590.19027153
3.0    -16590.18587074
3.5    -16590.17627193
4.0    -16590.16408747

this shows with 1.95 magnetic moment i got minimum energy -16590.19142434
Ry.


In my normal scf calculations with "runsp_lapw -ec 0.000001" command i got
minimum energy -16590.19143942 Ry.


Is this correct?


Please give me suggestions. Is there any another procedure?. If it is
please suggest me.

If i have to add a total energy in M=0. How to add it?.

Thank you very much.






On Mon, Mar 31, 2014 at 11:20 AM, Peter Blaha
<pblaha at theochem.tuwien.ac.at>wrote:

> Step 2) is the correct thing, but at least you should also add a total
> energy for M=0.
> And if the normal runsp calculation gives you the lowest total energy
> compared to all your fsm calculations, this is the proper solution.
>
> However:   do you know   WHY   you want to make a fsm calculation ?
>
> The  FSM method is used in 2 cases:
> a) The total energy of more than ONE magnetic/non-magnetic calculations is
> almost identical. You may see this in a normal scf calculation that it
> converges very slowly (or not at all) or the calculations of runsp_c and
> runsp (zero and finite moments) give almost the same energy.
> b) You obtained some solution with runsp, but you want to search for
> another (eg. a high-spin or low-spin) solution. In this case you have to
> estimate what would be the total moment of such an solution and search the
> corresponding M-range.
>
>
> On 03/29/2014 01:17 PM, Peram sreenivasa reddy wrote:
>
>> Dear WIEN2k,
>>
>>                      I am working on magnetic compound. For my system i
>> got total magnetic moment 1.95 bohr magneton. Now i want to do fixed
>> spin moment calculations.
>>
>>            My quires are
>> 1). To do fixed spin moment calculations, first i have to initiate the
>> calculations in spin polarized case after that i have to give the run
>> command like "runfsm_lapw -m 1.95 -ec 0.000001".
>> Is it correct way or give any suggestions?
>>
>> 2). To check weather this magnetic moment is correct or not i have to
>> take different magnetic moment values like 0.5, 1.0, 1.5, 2.0, 2.5, 3.0.
>> For all the values i have to run scf and check the total energy for each
>> fsm value. After this i have to plot total energy verses magnetic moment
>> values. In this plot where i get the minimum energy for a particular fsm
>> value, that magnetic moment value i should have to consider.
>> Is this correct procedure?
>>
>> Please suggest me further.
>>
>> Thank you very much in advance.
>>
>>
>>
>>
>>
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>>
> --
>
>                                       P.Blaha
> --------------------------------------------------------------------------
> Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
> Phone: +43-1-58801-165300             FAX: +43-1-58801-165982
> Email: blaha at theochem.tuwien.ac.at    WWW: http://info.tuwien.ac.at/
> theochem/
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