I am trying to analyze the CO2 adsorption on TiO2 substrate. Charge density difference is calculated using Δρ (r) = ρ(r){TiO2/CO2} - ρ(r) {TiO2} - ρ(r) (CO2). Literature have reported that while computing ρ(r) {TiO2} and ρ(r) (CO2), atoms needs to be kept fixed at precisely the same positions as they were in the adsorption complex. However, in my case significant distortion is occurred due to strong interaction between adsorbate and adsorbent, so it will not be possible to maintain the exact same position before and after the adsorption. Is there any alternate approach to deal with it? Any advice/suggestion will be greatly appreciated.
Thanks in Advance!
For details
http://www.fisica.uniud.it/~giannozz/QE-Tutorial/tutorial_postproc.pdf
For details
http://www.fisica.uniud.it/~giannozz/QE-Tutorial/tutorial_postproc.pdf
Thanks Alwin. But as you see in the exercise 4, atomic position of O atom and Al atoms is same as in they were initially. So it become very easy to directly subtract the charge density. However, in my case, position of atoms in the composite (TiO2/CO2) is different as adsorbate (CO2) and adsorbent (TiO2), which make it difficult to extract the charge density difference. Can you please suggest any alternate way to compute it ? If you need any further clarification, do let me know.
you must perform the three calculations on exactly the same atomic positions to avoid that.
Hello Karim, Thanks for your answer. But geometry of initial structure (isolated TiO2 and isolated CO2) is different from final structure (i.e after adsorption of CO2), so how it can be possible to perform the calculations on exactly same position ? Is there any trick you can suggest ?
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