Approximate Analytical Solutions for the Euler Equation for Second-Row Homonuclear Dimers

This work presents a new method how to obtain approximate analytical solutions for the Euler equation for second-row homonuclear dimers. In contrast to the well-known Kohn-Sham method where a system of N nonlinear coupled differential equations must be solved iteratively, orbital-free density functional theory allows to access the minimizing electron density directly via the Euler equation. For simplified models, here, an atom-centered monopole expansion with one free parameter, solutions of the electron density can be obtained analytically by solving the Euler equation at the bond critical point. The procedure is exemplarily carried out for N₂, C₂, and B₂, yielding bound molecules with an internuclear distance of 2.01, 2.43, and 3.07 bohr, respectively.