UT theoretical chemistry code forum

Hi,

I have a surface and a molecule above this surface. I need to calculate the charge transfer in VASP.

Are following steps correct?

1. Use special flags to get the correct CHGCAR that can be used in Bader analysis.
2. Calculate Bader Charge.
3. Do Step 1 & 2 for (a) Surface Only, (b) Molecule Only and (c) Surface + Molecule.
4. Charge Transfer = Bader Charge of (c) - Bader Charge of (a) - Bader Charge of (b)

Thanks for the help.

Yes, that is correct. You can also compare your Bader charges to the formal charges on the atoms. For example, you know that the total charge on your molecule will be the sum of the formal charges on the atoms in the molecule, without doing (b). But, if you want to know how charges redistribute within the molecule upon adsorption, then (b) would be needed.

Hi,

when I use the Bader analysis for the surface without adsorbate (a), must I use the electron density of the equilibrium surface or unrelaxed one?
This question is important because adsorption can significantly change the surface structure and these methods produce different results for the charge transfer.

Thank you in advance

Using the relaxed one would be better.

[quote="graeme"]Using the relaxed one would be better.[/quote]
Why?