QuantumATK Forum

QuantumATK => General Questions and Answers => Topic started by: Cyrille on August 31, 2015, 11:04

Title: Calculations with SOC
Post by: Cyrille on August 31, 2015, 11:04

Hi all

I have a question regarding calculations with spin-orbit coupling.
I am used to do such calculations with quantum-espresso and one needs a special relativistic pseudo to include SOC.
With ATK I have noticed that it is possible with the same openmx pseudo to perform both collinear (i.e. without SOC) and SOC calculations.
Does-it mean it is possible to "switch off" the spin-orbit coupling using a relativistic pseudo?
Or am I doing something wrong?

thanks in advance

Cyrille

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Cyrille Barreteau
CEA Saclay, IRAMIS, SPEC Bat. 771
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email:     cyrille.barreteau@cea.fr  /cyrbar@nanotech.dtu.dk
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Title: Re: Calculations with SOC
Post by: Anders Blom on August 31, 2015, 13:37

Yes. While it's a requirement to use the relativistic pseudopotentials to use spin-orbit coupling, you can use them in a collinear approximation just fine.

Title: Re: Calculations with SOC
Post by: Cyrille on August 31, 2015, 13:52

OK thanks that's a very good point.
It means that you can perform an initial collinear calculation to get a good starting point.

BTW is it possible to perform some tests calculations where SOC is multiplied by a given factor?

Cyrille

Title: Re: Calculations with SOC
Post by: Anders Blom on August 31, 2015, 15:02

Quote from: Cyrille on August 31, 2015, 13:52

It means that you can perform an initial collinear calculation to get a good starting point.

That is, in fact, precisely what you should do! :)

Quote from: Cyrille on August 31, 2015, 13:52

BTW is it possible to perform some tests calculations where SOC is multiplied by a given factor?

With DFT, the soc is computed from first principles, so no. I wasn't aware this was relevant, is it a technique used elsewhere? Refs?

Title: Re: Calculations with SOC
Post by: Cyrille on September 3, 2015, 14:57

By the way I have tried to start a SOC calculation from a collinear one using OMX pseudo and the 2014 version.
I get the following error:
Traceback (most recent call last):
  File "/tmp/7130187185888656.py", line 69, in <module>
    initial_spin=initial_spin, 
  File "./zipdir/NL/CommonConcepts/Configurations/AtomicConfiguration.py", line 1157, in setCalculator
NL.ComputerScienceUtilities.Exceptions.NLValueError: The initial state must have the same spin type as the new configuration.

Am I doing something wrong or is this option not available in 2014 version of ATK?

Cyrille

Title: Re: Calculations with SOC
Post by: Anders Blom on September 3, 2015, 14:58

Only available in 2015

Title: Re: Calculations with SOC
Post by: Cyrille on September 3, 2015, 15:12

OK thanks... We should get the 2015 licence soon in principle:-)