I need to calculate the charges (electron densities) on each atom of a set of partially fluorinated hydrocarbon molecules by NPA. The question arises:

What is the currently accepted / best practice method for validating these calculations as a function of Functional and Basis Set for DFT based calculations? Since no "experimental" values for electron densities are available, I have tried evaluating the "correctness" of the chosen functional and basis set by correlating the predicted bond lengths and bond angles to experimental values. However, this seems to be far too simplistic to provide a meaningful estimation of the correctness of the choice.

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    $\begingroup$ As you said in the question, electron densities and atomic charges do not have any strictly defined experimental measurement. In such cases, I often see people comparing results to a high level method, such as CCSD(T). You can try that if your molecules aren't too large. I have also heard of experimental estimation of atomic charges using NMR, I don't know how reliable or useful those are, but it's worth looking into. $\endgroup$
    – S R Maiti
    Commented Dec 22, 2021 at 20:53


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