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Re^8: unexpected energy curve from rsurface.

Dominic P. Guaņa
organicchemistry_01@yahoo.com.ph

Sorry for my lack of knowledge, I'am a graduating student major in physics and technology, I want to study on the adhesion of urea molecules with nickel surface but for this case my thesis only concerns on a single molecule of urea and a single atom of nickel, study concerning many body system will be for the next research, with this,

Thanks in advance...


On Sun Oct 25 '09 2:54pm, sanya wrote
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>Your system is really strange, you can get any results, none can be unexpected.

>First of all, the charge of the system is 0. Are you sure you are studying interaction of urea with Ni atom rather than with Ni2+ ion? With Ni2+, you may expect a coordination bond between O atom of urea and Ni2+ ion.

>Second, the multiplicity of the system is 1. Low-spin states (especially with Sz=0) are not typical for such transition metals as Ni. Are you sure you are interested in such a low-spin state? Try MULT=3 (triplet state), for example.

>Anyway, interaction of neutral subsystems (such as your urea molecule and Ni atom) in the absence of any strong specific interactions (such as coordination or hydrogen bonds) is mainly governed by Van der Waals forces, which are poorly reproduced by pure and hybrid functionals without dispersion correction. You used B3LYP, for which this is especially true. Note that dispersion-corrected functionals are not implemented in Firefly yet, you should try GAMESS-US.

>So, the problem may be in the charge of the system, its multiplicity, and functional used.

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