bader anlaysis for charged vacancy defect

Bader charge density analysis

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alokrs
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bader anlaysis for charged vacancy defect

Post by alokrs »

I want to do charge analysis for a neutral and charged vacancy of Ga in GaAs in VASP code. Here Ga is a charged vacancy that varies from +3 to -3 state. Is it possible to do Bader analysis for charged vacancy ?

Thanks

graeme
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Re: bader anlaysis for charged vacancy defect

Post by graeme »

Yes, for sure.

alokrs
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Re: bader anlaysis for charged vacancy defect

Post by alokrs »

Thanks for your reply. As per my unsderstanding bader will integrate total charge around each charge density maximum and write to a bader volume coresponding to that maxima. The ACF.dat file will list all atomic centers and electronic charges are summed together from nearest charge density maximums. I still have some doubt.

For neutral vacancy I removed one Ga atom from the GaAs system. Similarly for negative charged state of Ga -2 vacancy, I incresed default NELECT value by 2. Then from bader analysis how do I mesure total electronic charge at the vacancy site ? in oder to conform that neutral or -2 charge state of Ga is created.


Thanks and regards
Alok

graeme
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Re: bader anlaysis for charged vacancy defect

Post by graeme »

Ah, yes, I see what you are asking about.

It is quite possible that there will not be a charge density maximum at the vacancy site. If you are interested in the local charge of the vacancy as compared to the charge that may be delocalized throughout the crystal, you can look at the total charge of the As atoms around the vacancy site. Subtracting off the charge of the lattice As atoms will give you a measure of the charge at the vacancy site.

alokrs
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Re: bader anlaysis for charged vacancy defect

Post by alokrs »

graeme wrote:
" If you are interested in the local charge of the vacancy as compared to the charge that may be delocalized throughout the crystal, you can look at the total charge of the As atoms around the vacancy site. Subtracting off the charge of the lattice As atoms will give you a measure of the charge at the vacancy site. "
Sorry still not clear to me. Do you mean to say I have to do two calculations ?
1st one: - No defect in GaAs and find out total charge of As atoms.
2nd one: - with neutral or charged defect state, find the total charge of As atoms.
Subtract the total charge of As atoms from both the calculation. The resultant charge is the total charge at the vacancy site.

graeme
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Re: bader anlaysis for charged vacancy defect

Post by graeme »

No, I'm just saying that you can find the charge state of the vacancy from the sum of the charge on the neighboring atoms. Any extra or missing charge can be associated with the vacancy.

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