| 3:19:23 PM PST - Fri, Dec 9th 2016 |
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Jia,
I'm not sure what system you are studying, but in my work with transition metal complexes, the HOMO-LUMO degeneracy is usually an indication that symmetry will be broken by a Jahn-Teller distortion. In this case, it is better to "break" the symmetry to a lower point group and allow the HOMO and LUMO to split in energy. This doesn't necessarily mean disabling symmetry outright - a Jahn-Teller distortion can leave the molecule in a subgroup of the original point group provided that the HOMO-LUMO degeneracy is broken.
Best,
James
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