CCL:G: About antiferromagnetic coupling

 Sent to CCL by: Serge Gorelsky [gorelsky,,]
 > Dear CCLers:
 > Â I'm new to Gaussian,so I try to reproduce some example at Gaussian's
 > website.But I'm confused about one.In the "Antiferromagnetic
 > example of tries to
 > reorder the orbitals,and choose some Âorbitals changed to .What I'm
 > confused is the criterion that it choose the orbitals to be reordered.Why
 they choose these orbitals to be reordered.
 yes, that's indeed a confusing method. A much better (simpler and 100%
 reliable) method is to take fragment orbitals and generate an
 appropriate guess wavefunction. See Appendix II of the AOMix manual
 ( for details.
 Best regards,
 Â Serge Gorelsky