Local exchange fraction & g in DDHCustomExchangeCorrelation

[sukhito teh]

Dear users and developers,
Is there a way to extract local g or local exchange fraction when implementing local dielectric dependent hybrid in DDHCustomExchangeCorrelation? It would be useful for analysis or fitting ddh paramters.

I also tried to calculate the alpha based on the average g using the attached script, however the value always  differ ( usually about 10%) from the value given by ...exchangeCorrelation().exactExchangeFraction(). Other than that, I also wonder if there's a faster way to obtain derivative of electron density other than using the iteration method as stated in the attached script.
Thank you and have a nice day.

[Anders Blom]

We are planning to support this analysis in a future version of QuantumATK. For now, you can use the attached compiled module. The file also contains an example of how to use it.
The alpha values are saved as a real-space 3d grid in the HDF5 file, and can be analyzed as usual in NanoLab via the Grid Tool etc

[sukhito teh]

We are planning to support this analysis in a future version of QuantumATK. For now, you can use the attached compiled module. The file also contains an example of how to use it.
The alpha values are saved as a real-space 3d grid in the HDF5 file, and can be analyzed as usual in NanoLab via the Grid Tool etc

Thank you for the quick response, this is really helpful. Have a nice day.

[sukhito teh]

We are planning to support this analysis in a future version of QuantumATK. For now, you can use the attached compiled module. The file also contains an example of how to use it.
The alpha values are saved as a real-space 3d grid in the HDF5 file, and can be analyzed as usual in NanoLab via the Grid Tool etc

Dear Mr Blom,
According to this paper (https://pubs.acs.org/doi/abs/10.1021/acs.jctc.7b00853), they neglect the derivatives of mixing functions to save computational costs, thus the forces cannot be treated as derivative of energy. QATK doesn't support force calculation for this exchange correlation either, does the same approximation has been used in QATK?

[Anders Blom]

Correct, we follow the same idea as in the paper you mention