Corrections for Functionals

It is possible to derive tunnel corrections for functional forms of the energy barrier other than an inverted parabola, but these cannot be expressed in analytical form. Since any barrier can be approximated by a parabola near the TS, and since tunnelling is most important for energies just below the top, they tend to give results in qualitative agreement with the Bell foimula. 

It is possible to derive tunnel corrections for functional forms of the energy barrier other than an inverted parabola, hut these cannot he eypressed in analytical form. Since ... 

The most familiar correction for functionals may be the self-interaction correction, which removes the self-interaction error of exchange functionals. In density functional theory, the self-interaction error indicates Coulomb self-interactions, which should cancel out with the exchange self-interactions but remain due to the use of exchange functionals as a substitute for the Hartree-Fock exchange integral in the exchange part of the Kohn-Sham equation. 

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