Dear Wien2k users,

I want to explain the negative temperature co-efficient of Co50Ga50 alloy
using DFT. For this, I have run the SCF calculation using experimental XRD
parameters with simple spin polarized case. Although, I have seen a sharp
fall of DOS around the Ef in total DOS, there have been a few DOS
available. Hence, to explain the semiconductor like nature of this alloy, I
thought to apply Ueff procedure to create artificial gap around Ef. The
Ueff was applied to the d-states of Co atom only as most of the states
around the Ef are from the Co-d-bands.

For a typical SCF calculation (ie, Ueff= 0 eV), the Co d-t2g forms he
bonding states and Co d-eg forms the anti-bonding states around the fermi
level. I was expected a formation of band gap as both d-t2g and d-eg states
are separate due to application of Ueff. However, in this case, d-t2g
states are only moved well below the fermi level while d-eg are not
effected. As Fermi level crosses at d-eg states, no gap was seen even for
Ueff = 5 eV. Please see the attached data for both Ueff values.

My doubt is, why Ueff applies only on d-t2g and why not on both. If this is
the case, how can I approach to move both d-t2g and d-eg states together.

please give me some suggestions on this problem.



Attachment: Co50Ga50_Co_d_eg.pdf
Description: Adobe PDF document

Attachment: Co50Ga50_Co_d_t2g.pdf
Description: Adobe PDF document

Attachment: Co50Ga50_d_eg_Ueff=5eV.pdf
Description: Adobe PDF document

Attachment: Co50Ga50_d_t2g_Ueff=5eV.pdf
Description: Adobe PDF document

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