Hi everyone

I'm doing a kind of simulation on DMol3, where I didn't have problem while I was using molecules without charge. However when I set a charge on the system, the result is not ok.

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1^st simulation: optimization of two molecules (C60 + HOOH), after that I need to find out the adsorption energy by the following formula

E(C60 + HOOH) – E(C60) – E(HOOH)

Conclusion: when the molecule (HOOH) approaches from the C60 molecule, there is an increase of the repulsion energy; when the molecule (HOOH) a moved far away from the C60 molecule there is an increase of the repulsion energy. But when the HOOH molecule is much far of the C60 the adsorption energy tends to zero, i.e. the plot (Adsorption Energy  X distance between the centroids) is a Lennard- Jones potential curve.

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2^nd simulation: optimization of two molecules (C60 + HOO(-)), after that I need to find out the adsorption energy by the following formula

E(C60 + HOO(-)) – E(C60) – E(HOO(-))

Conclusion: The difference now is the charged HOOH molecule. When I do all the steps the Lennard-Jones Potential curve appears, but with one problem: the adsorption energy do not tend to zero when the HOO(-) is much far from the C60.

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Question: Why the DMol3 are not working to simulations that involves charged molecules? How do I fix it?