[Wien] Calculation spin-orbit coupling with two different approach gives different results
Santu Baidya
santubaidya2009 at gmail.com
Mon Nov 23 16:12:14 CET 2015
Dear Prof. Laurence Marks,
Thank you very much for your reply. So at the end I would like to ask you
that in my cases :MVORD are less than 1%. So I have to choose lowest energy
case.
Thanking you and with regards,
Santu Baidya
On 23 November 2015 at 20:33, Laurence Marks <L-marks at northwestern.edu>
wrote:
> With those values of :MVORD you are "OK", it is self-consistent. As my
> email said large percentage values are an indication of convergence to a
> trap.
>
> On Mon, Nov 23, 2015 at 8:26 AM, Santu Baidya <santubaidya2009 at gmail.com>
> wrote:
>
>> Dear Prof. Laurence Marks,
>>
>> Thank you very much for your suggestion. I just checked "grep :MVORD
>> ". It gives
>>
>> :MVORD NDM 150 L1 2.800091E-06 % 5.2649E-02 when started from
>> collinear ground state.
>>
>> Same estimate "grep :MVORD " gives
>>
>> :MVORD NDM 150 L1 1.028089E-05 % 1.3122E-01 when started from
>> scratch.
>>
>> So for both cases :MVORD is less than 1% ?
>>
>> Please enlighten this little more.
>>
>>
>>
>> Thanking you and with regards,
>>
>> Santu Baidya
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>> On 23 November 2015 at 19:31, Laurence Marks <L-marks at northwestern.edu>
>> wrote:
>>
>>> Let me add one small thing to what Peter said. Be careful to check that
>>> you truly have a converged density. It is possible for the scf iterations
>>> to converge to a trap where the density (:DIS etc) is converged but the
>>> orbital terms (:MVORD) are not self-consistent. I would estimate that for a
>>> self-consistent orbital potential :MVORD should be less than 1%. It can be
>>> necessary to take some measures to climb out of local traps like this, for
>>> instance by doing "echo 0.1 > .pratt" to force a Pratt step to be included.
>>> This can be important when -so is included, and in a few cases when it is
>>> not.
>>>
>>> On Mon, Nov 23, 2015 at 7:45 AM, Santu Baidya <santubaidya2009 at gmail.com
>>> > wrote:
>>>
>>>> Dear Prof. Blaha,
>>>>
>>>> Thank you very much for you reply on this. Actually I did relax the
>>>> structure under GGA+U approximation. Then took two approaches. In one case
>>>> I did SCF calculation under GGA+U with relaxed structure and added SOC
>>>> afterthat. In other case I took relaxed structure and did GGA+U+SOC
>>>> calculation.
>>>> Which gave me two different electronic structure for the same relaxed
>>>> structure.
>>>>
>>>> So I have to take lowest energy structure.
>>>>
>>>> Thanking you and regards,
>>>>
>>>> Santu Baidya
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> On 23 November 2015 at 18:58, Peter Blaha <pblaha at theochem.tuwien.ac.at
>>>> > wrote:
>>>>
>>>>> It is well know that GGA+U calculations can end up in different states
>>>>> (see previous posts).
>>>>>
>>>>> If you have used the same parameters, you should use the total
>>>>> energies of the two calculations and the one with lower energy should be
>>>>> the better one (but not necessarily the best !)
>>>>>
>>>>> In any case, I always recommend:
>>>>>
>>>>> First do a standard GGA calculation (also check forces, if they are
>>>>> small).
>>>>> Then add SO and do a GGA+SO calculation (if you really have heavy
>>>>> elements?)
>>>>> x lapwdm -up -so to generate density matrices
>>>>>
>>>>> and finally add the "U" and do GGA+so+U
>>>>>
>>>>> There is, however, no guarantee that you find the lowest energy ground
>>>>> state ! Sometimes it is good to start with a smaller U-value than
>>>>> anticipated.
>>>>> Sometimes you may do a structure relaxation at the GGA-level and use
>>>>> this structure,
>>>>> or a structure relaxation at GGA+U (no SO).
>>>>>
>>>>> If SO is not a major effect, I'd first do everything without SO.
>>>>>
>>>>> -------------------
>>>>> From these advices you can see that there is not a unique and save
>>>>> way, which works in all cases.
>>>>>
>>>>>
>>>>>
>>>>> On 11/23/2015 12:10 PM, Santu Baidya wrote:
>>>>>
>>>>>> Dear Prof. Blaha and wien2k users,
>>>>>>
>>>>>> I use wien2k version WIEN2k_14.1. Recently I did spin-orbit
>>>>>> coupling calculation under GGA+U+SOC approximation with two different
>>>>>> approaches- one starting from collinear ground state and another
>>>>>> starting from scratch (random wavefunction). Two approaches give me
>>>>>> completely different results -metal and insulator.
>>>>>>
>>>>>> Please tell me which approach should I accept as solution.
>>>>>>
>>>>>> I look forward to get reply.
>>>>>>
>>>>>> Thanking you,
>>>>>>
>>>>>> Santu Baidya
>>>>>> University of Duisburg-Essen
>>>>>> Duisburg
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>> _______________________________________________
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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 WIEN2k: http://www.wien2k.at
>>>>> WWW: http://www.imc.tuwien.ac.at/staff/tc_group_e.php
>>>>>
>>>>> --------------------------------------------------------------------------
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>>>>>
>>>>
>>>>
>>>
>>>
>>> --
>>> Professor Laurence Marks
>>> Department of Materials Science and Engineering
>>> Northwestern University
>>> www.numis.northwestern.edu
>>> Corrosion in 4D: 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
>>>
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>>>
>>
>
>
> --
> Professor Laurence Marks
> Department of Materials Science and Engineering
> Northwestern University
> www.numis.northwestern.edu
> Corrosion in 4D: 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
>
> _______________________________________________
> Wien mailing list
> Wien at zeus.theochem.tuwien.ac.at
> http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
> SEARCH the MAILING-LIST at:
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>
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