PDOS

[alberto]

Hi cp2k users, 

I run a PDOS calculation with PBE functional for the Yb:YAG system.

Unfortunatley the band gap is understimated and it has an approximate value of 4 eV rather than about 6.4 eV.

This what I see (in black O,  in red Y, in green Al and in blu Yb)

This is the band gap of YAG of 6.4 eV which I expect also for Yb:YAG.

I think that GGA functionals are at a too much lower theory level for accuratley describe the energy gap and consequently the 4f energies splitting of Yb(III) which finally I want to calculate.

I would want to try the hybrid functional HSE06, but I don't know which pseudopontentials are correct to use for O, Al, Y, Yb.

I don't find the HSE06 pseudopotentials for Y, Al, O, Yb.

I attach my input for PDOS calculation with PBE.

There are evident mistakes? 

Sorry but this is one of the first times that I perform PDOS calculation in general.

Thanks a lot 

Alberto 

[Debmalya Ray]

Hi Alberto,

This is well known that PBE underestimates the bandgap. I tried to do some HSE06 calculation recently but it was really slow for my system. You could try to use some PBE+U calculation and you will have better agreement with experimental values. If it's an oxide system I would recommend using ~U= 4 eV for Yb 4f orbitals.

Best,

Debmalya

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[alberto santonocito]

Thanks a lot for your very helpful answer.

Alberto 

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