Most intro explanations of molecular orbital formation go something like this: as two 1s orbitals of H atoms approach each other, their wave functions begin to overlap, and due to constructive and destructive interference, a bonding and an anti-bonding orbital is formed.

Since initially there can be an arbitrary difference in phase between the two 1s orbitals, does this mean that the energy of the molecular bond is a function of the phase difference and that a bonding orbital will form only for a range of phase differences ?

  • $\begingroup$ There is no range. The phases can be either similar or opposite. $\endgroup$ – Ivan Neretin Dec 4 '17 at 17:17
  • $\begingroup$ And either a bonding MO forms (AOs are in phase) or an anti-bonding MO forms (AOs are of opposite phase). And what @IvanNeretin said. $\endgroup$ – Gert Dec 4 '17 at 17:27
  • $\begingroup$ OK.... but why? $\endgroup$ – Tomek Dobrzynski Dec 4 '17 at 18:42
  • $\begingroup$ Because all other combinations do not produce eigenfunctions. $\endgroup$ – Ivan Neretin Dec 4 '17 at 18:44
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    $\begingroup$ @M.ghorab. From that article: In general, the energy difference between a bonding and anti-bonding orbital pair becomes larger as the overlap of the atomic orbitals increase. $\endgroup$ – Tomek Dobrzynski Dec 5 '17 at 13:15

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