QuantumATK Forum

QuantumATK => General Questions and Answers => Topic started by: issac7 on October 20, 2023, 09:46

Title: Question about the distances in the SlaterKosterTable
Post by: issac7 on October 20, 2023, 09:46

Dear sir,

I'm doping DFTB calculations based on user specified Slater-Koster matrix according to

https://docs.quantumatk.com/tutorials/slater_koster/slater_koster.html#slater-koster-tight-binding-models-in-atk-se (https://docs.quantumatk.com/tutorials/slater_koster/slater_koster.html#slater-koster-tight-binding-models-in-atk-se).

Here is my question: what does the distance "d" stands for?

I'm confused because the specified d is actually out of the nearest distance between atoms.

Code

# Setup list of distances
epsilon = numpy.linspace(-0.20, 0.20, 41)
distances = [ d_n1*(1.0+x) for x in epsilon ] + [ 0.5*(d_n1+d_n2) ]

Looking forward to your replies. Thanks a lot.

Title: Re: Question about the distances in the SlaterKosterTable
Post by: Anders Blom on October 24, 2023, 01:38

I think the code speaks for itself. d_n1 is the first nearest neighbor distance, d_n2 the second.

Title: Re: Question about the distances in the SlaterKosterTable
Post by: issac7 on October 24, 2023, 07:07

Thanks for replying. Sorry for the unclear question. The "d" I put earlier means the <distances=...> in the code. I am confused that the distances that determined the offsite hopping matrix fall out of the nearest atomic distance.

Title: Re: Question about the distances in the SlaterKosterTable
Post by: Anders Blom on October 24, 2023, 19:26

The distances variable basically does two things. It creates a range around the nearest distance, where either the interaction will be constant (to catch any small numerical difference in distances) or a (d/d0)^2 fall-off which is common in these models. The final point is to truncate the interactions at some large distance, it is paired with a zero-term in the hopping elements.