In this task you will be given a text passage from a trivia quiz. You should choose the category this question belongs to from these categories: History, Science, Social Science, Fine Arts, Literature. You can only choose one category, so if in doubt, please choose the closest match.
Q: A 2004 paper attempted to derive superconductivity in some materials from the interactions of "small polarons" named for this effect arising from large electron-intermolecular vibration coupling in the presence of an intramolecular vibration. Certain electronic transitions in some species are unexpectedly weakly Laporte-allowed due to this effect, which also provides copper's place as highest on the high-spin Irving-Williams series. This phenomenon predicts the insulating activity of certain metal-doped fullerene species. A radical anion of cyclooctatetraene exhibits this effect. A weaker version of this effect occurs with species like scandium (I), since the t2g set does not point at any ligands. This phenomenon occurs most strongly in high spin d4, low spin d7, and d9 complexes. For 10 points, identify this phenomenon that occurs principally in octahedral geometries to prevent asymmetrically occupied orbitals from having degenerate energy levels by stretching one axis.
A:
Science