Author Topic: DFT-1/2 default parameters  (Read 82 times)

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Offline NW

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DFT-1/2 default parameters
« on: August 26, 2021, 09:52 »

I have a question regarding DFT-1/2 default parameters for each element. Since we need to consider the surrounding atoms of specific element in each compound, I was wondering how QuantumATK deals with that. Does it considere default values for each element regardless of the surrounding atoms or it automatically adjusts the parameter based on the surrounding atoms?


Offline Anders Blom

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Re: DFT-1/2 default parameters
« Reply #1 on: August 27, 2021, 00:57 »
The +1/2 parameters are fixed and atom-specific, not environment-dependent. However, that doesn't mean that the +1/2 method itself is environment-agnostic; the self-consistent density and potential do enter into the integrals. If you had to adjust the parameters self-consistently, it would make the method unbearably slow and probably wouldn't even change the results much. One can actually see a parallel in DFT itself, where the pseudopotentials do not depend on the environment but the DFT calculation as a whole does, or for another example we use the same pseudopotentials for all different flavors of GGA functionals, although in theory one could attempt to find a specific pseudopotential (and then basis set) for PBE, revPBE, and so on. But these are the things we avoid in order to make DFT a practical method.