QuantumATK Forum

QuantumATK => General Questions and Answers => Topic started by: sitangshu on July 17, 2015, 07:49

Title: Bader charges computations
Post by: sitangshu on July 17, 2015, 07:49

Dear Quantumwise,

I see that in the feature list at
http://quantumwise.com/products/features
there is an option to analyze the charge transfer procedure through Bader's method.  We are using currently 2014.1 version. Is it included as "charge" in FHI-AIMS of this version or should I download the 2015 version?

Title: Re: Bader charges computations
Post by: Umberto Martinez on July 17, 2015, 08:23

NO, you can use VNL and ATK 2014. However, please update to the latest release 2014.2 which you can find on our website available for download.

Title: Re: Bader charges computations
Post by: Dipankar Saha on July 17, 2015, 21:17

Dr. Umberto Martinez,

1) Being Full-potential in all electron scenario....how do you tune the "Accuracy"  (as, we find medium to ultra...with Tier 1 to Tier 3) ??
2) What if, in a composite-system... one of the materials is metallic and the other one is Insulator ?!!

Regards_
Dipankar

Title: Re: Bader charges computations
Post by: Dipankar Saha on July 17, 2015, 21:24

Besides,  I wanted to know_

Has there any VW correction for PBE (such as, Tkatchenko-Scheffler interatomic dispersion .....) been implemented as of now??

Title: Re: Bader charges computations
Post by: Jess Wellendorff on July 20, 2015, 14:25

I believe your questions are related to the FHI-aims calculator.

We should take great care not to confuse ATK with FHI-aims. ATK is a platform that includes several different computational engines, including ATK-DFT, ATK-semiempirical, and ATK-classical. FHI-aims is another engine for first principles calculations, developed at the Fritz-Haber Institute in Berlin. You can set up, run, and analyze FHI-aims calculations using the VNL interface, but your ATK licence must include access to FHI-aims for this to work.

1) FHI-aims accuracy is tuned mainly by increasing the basis set size and by using increasingly dense integration grids.
2) What matters is the expected electron distribution around the Fermi level of the full system, not the individual parts of it. Is the full system an insulator or conductor? In any case, both options may often work rather well.
3) ATK offers the Grimme DFT-D method, while FHI-aims also implements the TS and vdW-DF methods for van der Walls interactions.

Title: Re: Bader charges computations
Post by: sitangshu on July 20, 2015, 15:45

Dear Jess,

Thanks for your reply. Incidentally, we are studying the interface of semiconductor/insulator/amorphous metal oxide. It seems the DFT procedure is working well for charge distribution analyses.

Title: Re: Bader charges computations
Post by: nahid khadempar on July 21, 2015, 19:20

hello,good time..
 excuse me , I cant find any Information about the Conversion between hexagonal and
 simple orthorhombic settings....please guide me..thanks for your help.

Title: Re: Bader charges computations
Post by: Anders Blom on July 22, 2015, 00:32

See http://quantumwise.com/publications/tutorials/item/99-commensurate-supercell-for-rotated-graphene-layers

You could also try https://www.google.com/search?site=&source=hp&q=transform+hexagonal+cell+to+orthorhombic+in+virtual+nanolab&oq=transform+hexagonal+cell+to+orthogonal+supercell+in+virtual+nanolab

Searching is often quicker than asking ;)

Title: Re: Bader charges computations
Post by: Dipankar Saha on July 22, 2015, 22:18

Thank you very much  Jess ...!!!  / Yeahhh...I already knew the license isuue .... :)

All I was  wondering about the  O (N) scaling ...instead of O (N³) ...!!! Would it allow me to use large no. of atoms?

I got your points..what you have mentioned otherwise..!!!

Regards_
Dipankar