QuantumATK Forum

QuantumATK => General Questions and Answers => Topic started by: ramkrishna on May 3, 2016, 18:12

Title: Region dependent mole fraction
Post by: ramkrishna on May 3, 2016, 18:12

Hi,
Is it possible to set region-dependent "x" parameter (i.e. mole fraction) in VCA calculation?

Thanks
Ramkrishna

Title: Re: Region dependent mole fraction
Post by: Jess Wellendorff on May 4, 2016, 09:11

Yes, you can to some degree introduce region-dependent mole-fraction for VCA. I guess you have already seen the tutorial http://quantumwise.com/publications/tutorials/item/852-virtual-crystal-approximation-for-ingaas-random-alloy-simulations.html (http://quantumwise.com/publications/tutorials/item/852-virtual-crystal-approximation-for-ingaas-random-alloy-simulations.html). VCA basis sets are constructed as "VirtualCrystalBasisSet([in_basis,as_basis], x=0.5)". You can create more than one such VCA basis in the same script, with varying "x". Then use tagging of the atoms to attach different VCA basis sets to different atoms. I have attached a script that shows how this is done.

Title: Re: Region dependent mole fraction
Post by: Jess Wellendorff on May 4, 2016, 09:15

Just to clarify: I expect the method outlined above will work for your purposes, but you should check it carefully before relying on it :)