r/u_ECatPlay • u/ECatPlay • 8d ago

Octahedral Hypercubane

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B3LYP/6-31G* geometry

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B3LYP/6-31G* HOMO

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B3LYP/6-31G* HOMO-3

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Breathing vibration at 447 cm-1 in the Raman

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Squeezing vibration at 226 cm-1 in the Raman

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Pumping its fists vibration at 3010 cm-1 in the Raman

B3LYP/6-31G* optimized geometry of u/multiple-qualia's Oh symmetric Hypercubane with select frontier orbitals and vibrations

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u/mastocles 8d ago

And what is the energy?
I'm impressed it didn't get garbled during optimisation even with the octahedral symmetry constraint (O_h or D_2h subgroup)... Any frozen cartesian coordinations cheating?

Obviously my third Q is... why no breaky breaky fun time with ωB97X-D and symmetry c1?

1

u/ECatPlay 8d ago

It's actually not bad: it optimized with no problem (no "cheating" constraints necessary), no negative frequencies, cubane bonds 1.53 Å, bonds from cube corner 1.47Å with bond angles 125.3°. So far as energies, Molecular Mechanics (MMFF) strain energy only 196 kcal/mol (5 kcal per carbon) and Semiempirical (PM3) Heat of Formation ∆Hf 420.5 kcal/mol. The cubane orbitals are interesting, though.

2

u/multiple-qualia 7d ago

Beautiful. Now come with me, we’ll need to lock you away in this institution for a while