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Hello everybody,
I tried many time to get reasonable adsorption energy of a molecule on a particular substrate. But I get smaller adsorption energy using VASP than what people have reported using different computational software like Gaussian.
Could anyone tell me what wrong is going on my calculations or what? I used the maximum cut off energy, enough k-points enough vacuum thickness ( 15Angs) , etc .
I thank you

please mind that Gaussian is a very different method. For small
molecules, it may be necessary to use hybrid functionals (which will be included in vasp.5).
Also: have you at all tested which would be the best psedopotential to use for your purpose? For molecule adsorption, usually PAW-PBE is best