Kato theorem

The Kato theorem, or Kato's cusp condition, is used in computational quantum physics. It states that for generalized Coulomb potentials, the electron density has a cusp at the position of the nuclei, where it satisfies

Here ${\displaystyle \mathbf {R_{k}} }$ denotes the positions of the nuclei, ${\displaystyle Z_{k}}$ their atomic number and ${\displaystyle a_{o}=\left({\frac {h}{2\pi me}}\right)^{2}}$ is the Bohr radius.

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