Is there somewhere in the internet a good simple free working code (with a minimal number of lines in its presentation) that implements a calculation of eigenvalues with Hartree–Fock (or DFT) algorithm for $\ce{H2}$, $\ce{He}$, $\ce{Li}$, $\ce{H2O}$, $\ce{CO2}$ (or something else, something simpl...