Orbital Energies and Nuclear Forces in DFT: Interpretation and Validation

24 June 2020, Version 1
This content is a preprint and has not undergone peer review at the time of posting.


The bonding and antibonding character of individual Molecular Orbitals has been previously shown to be related to their orbital energy derivatives with respect to nuclear coordinates, known as Dynamical Orbital Forces. Albeit usually derived from Koopmans' theorem, in this work we show a more general derivation from conceptual DFT, which justifies application in a broader context. The consistency of the approach is validated numerically for valence orbitals in Kohn-Sham DFT. Then, we illustrate its usefulness by showcasing applications in aromatic and antiaromatic systems and in excited state chemistry. Overall, Dynamical Orbital Forces can be used to interpret the results of routine ab initio calculations, be it wavefunction or density based, in terms of forces and occupations.


Molecular Orbital Analysis
Molecular Orbitals
Density Functional Theory
Koopmans Theorem
Nuclear Forces


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