I'm making a topological analysis of a nanotube interacting with some metals.

The steps for the calculations were:

  • Optimizing the geometry (I am using SIESTA code).
  • Obtain the electronic density for the final relaxed structure (in cube format with the help of DENCHAR utility that is part of the SIESTA distribution): density files for total electron density (RHO), spin up electron density (RHO.UP) and spin down electron density (RHO.DOWN).
  • Run topological analysis with CRITIC21,2 software.

For the three metals under study, I got a bond critical point from the RHO file.
When analyzing the RHO.UP and RHO.DOWN files, for two metals I got two critical points (one for each spin). But for one metal, I only got one bond critical point.

As the recommended way to run topological studies is using the wavefunction directly instead the electron density, I run the topological analysis from density files with different grid size.

The question: Can I have a bond formed for only one spin?


1 A.Otero-de-la-Roza, M.A.Blanco, A. Martín Pendás, Víctor Luaña. Critic: a new program for the topological analysis of solid-state electron densities, Computer Physics Communications Volume 180, Issue 1, January 2009, Pages 157-166. DOI: 10.1016/j.cpc.2008.07.018

2 A.Otero-de-la-Roza, Erin R.Johnson, Víctor Luaña, Critic2: A program for real-space analysis of quantum chemical interactions in solids, Computer Physics Communications Volume 185, Issue 3, March 2014, Pages 1007-1018. DOI:10.1016/j.cpc.2013.10.026


Yes, see e.g. the hydrogen molecule cation.

  • 1
    $\begingroup$ Can you share any reference about? Thanks. $\endgroup$ – Camps Apr 5 at 20:28
  • $\begingroup$ Reference for what? $\endgroup$ – Susi Lehtola Apr 6 at 0:01

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