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I am doing DFT calculations (VASP) to calculate correct binding energy for an amorphous silica surface and silver adatoms. From MD simulation, we found that a binding energy of 0.2 eV gives results which can be matched to experimental ones.

Since this is an amorphous surface, how do I go along to measure the correct binding energy. I have tried 18 runs where I have relaxed the adatom at different positions and at different heights but how many runs to do this as each result has a different value?

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  • $\begingroup$ Maybe I misunderstand your question, but why you don't stick to MD simulations? $\endgroup$ – user23061 Jun 6 '16 at 14:02
  • $\begingroup$ What, precisely, do you want to know? For an amorphous surface one would expect a range of binding energies because each surface 'site' is a little different from the others. So, you are looking at a spread of binding energies and you would need to characterize the shape of that spread. Now, you will also have to consider the possible errors and variation in DFT itself, which can be considerable depending on the system. $\endgroup$ – Jon Custer Jun 6 '16 at 15:01
  • $\begingroup$ Yes, the binding energy value is an average over the surface. I want to do DFT so as to see whether I get a similar value of binding energy that I did in MD. Also to know the bond length between the atoms but what I have observed is that the spread is too large and the values are quite high. I am confused on how to accurately determine these two. $\endgroup$ – Curious Jun 6 '16 at 21:00

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