You must create a fake atom: For instance, in the Ga_x Al_1-x As alloys, you must create a fake cation that represents the mixture Ga_x Al_1-x, by changing Z, mass and number of electrons accordingly. Then you can run all wien2k the steps. Look at http://www.mail-archive.com/[email protected]/msg09734.html!!

Thanks a lot sir for your kind reply

I want to know how does the VCA method work, compared with other method like supercell run by VASP or compared with experimental data? Thanks.

you can do it in VASP(https://www.vasp.at/wiki/index.php/VC)A and CASTEP( https://www.tcm.phy.cam.ac.uk/castep/documentation/WebHelp/content/modules/castep/thcastepdisorder.htm)

I want to perform DFT of RHEAs using SQS and VCA method. I donot know how to build SQS structure before performing DFT. Can anyone guide me how to do that. Thanks