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What are the types of charge analysis?
19 votes

Just to add to the discussion: Mulliken charges are flawed in many aspects, but we know how and why, and therefore we accept its use, since it is simple and easily computed. But very dependent on the ...

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Can DFT be considered an ab initio method?
9 votes

As pointed out by several people already, some information can be found elsewhere, as in here. And also the differentiation between DFT (exact) and density functional approximations (DFAs), as pointed ...

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What are the types of bond orders?
8 votes

It depends on what you want from it. If you're an organic chemist, you'd be mostly interested in the type of bond (single, double, triple, aromatic), and for that the bond order is most relevant (but ...

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How to canonicalize SMILES written with aromatic bond symbols (:)?
7 votes

I think it might be good to have a look at SELFIES by Alan Aspuru-Guzik and co-workers: From what I remember from his talk in Girona last December, this ...

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A CCSD(T) geometry optimization in Gaussian09 is deviating too far from the minimum. How do I deal with it?
5 votes

I'm always using CFOUR for CCSD(T) calculations, so bear with me. With CFOUR you can actually specify the irrep occupations, and works very well for the optimizations. But, there is one big snag. You ...

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What is the closest thing we have to "the" universal density functional?
4 votes

Probably this recent paper by James Kirkpatrick, Aron Cohen and co-workers is getting closest to it: "Pushing the frontiers of density functionals by solving the fractional electron problem",...

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Is this G16 molecular hyperpolarizability error reproducible in other software?
4 votes

Since the basis set seems to play a big role, from my paper (1999): "A lot of effort has been put into constructing basis sets specially designed for accurate calculations of the polarizability [...

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