Hydrogen molecules nuclei interaction integrals

Fig. R.2. The hydrogen molecule in the simplest basis set of two Is STOs. (a) The overlap integral 5 as a function of the internuclear distance R (b) the penetration energy represents the difference between the electron-proton interaction calculated assuming the electronic charge distribution and the same energy calculated assuming the point charges (the electron is located on the nucleus c) (c) the energies + and E- of the bonding (lower curve) and of the antibonding (upper curve) orbitals, respectively.

---