There exists a free online orbital calculator.

When I draw cyclopropane it plots three molecular orbitals, but unfortunately it doesn't use the Walsh orbitals.

Are there any free online tools which can solve such the problem?

(It would be very nice if it would also be an android app. Please let me know if you know one.)

The section below is for interested chemists:

The reason why I want to do that:

Cyclopropane can, to a good approximation, be described with the following orbitals:

enter image description here

The question was how the molecule orbitals behave if we add an electron withdrawing group (a $\pi$ acceptor because some people call it the "CXZ model")

enter image description here

The solution says:

In the substituted case all energy levels are lying more down in energy.

I don't agree because I only see overlap with the Walsh Möbius set of $sp$ orbitals in the following sketch:

enter image description here

The Hückel set (a simpler way to put it: the energy lowest orbital in the scheme of cyclorpropane; used above) gives no overlap with the $p$ orbitals of an electron withdrawing group, e.g. X=COOH.

As I see from the orbitals' interaction, I believe the solution is wrong, I don't agree that all orbitals are lowered.


  1. Sorry for the mistake in the sketch, there is of course only one of the two degenerate Möbius orbitals lowered.
  2. I guess COOH not only has a $\pi$ acceptor effect but also a $\sigma$ acceptor effect which could lower all orbitals.
  • 3
    $\begingroup$ Don't know if this help but you can compute the canonical MOs (at the RHF/STO-3G//PM3 level of theory) using molcalc.org $\endgroup$ – Jan Jensen Jun 19 '15 at 10:41
  • $\begingroup$ Related: chemistry.stackexchange.com/a/10655/4945 $\endgroup$ – Martin - マーチン Jun 19 '15 at 12:08
  • $\begingroup$ @JanJensen I tried your page, however I like to get a graphical interface similar as in my SHMO solver, so I don't have to manually plot the energy levels. If there exist a freeware for Windows, which can easily do that (or an Android app) I would also be interested in. $\endgroup$ – laminin Jun 19 '15 at 14:31

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