## overlap integral, $$S_{\text{rs}}$$

https://doi.org/10.1351/goldbook.O04357
Integral over space of the type $$\int \psi _{\text{r}}^{*}\ \psi _{\text{s}}\ \text{d}\tau$$ where $$\psi_{\text{r}}$$ and $$\psi_{\text{s}}$$ are different wavefunctions.
Source:
Green Book, 2nd ed., p. 17 [Terms] [Book]