In quantum mechanics, a shape resonance is a metastable state in which an electron is trapped due to the shape of a potential barrier.[1]
Altunata[2] describes a state as being a shape resonance if, "the internal state of the system remains unchanged upon disintegration of the quasi-bound level."
A more general discussion of resonances and their taxonomies in molecular system can be found in the review article by Schulz;[3][4] for the discovery of the Fano resonance line-shape[5] and for the Majorana pioneering work in this field[6] by Antonio Bianconi; and for
a mathematical review by Combes et al.[7]
^Bianconi, Antonio (2003). Ugo Fano and shape resonances. X-ray and Inner Shell Processes (19th Int. Conference Roma June 24–28, 2002). Unsolved Problems of Noise and Fluctuations. Vol. 652. AIP. p. 13. arXiv:cond-mat/0211452. doi:10.1063/1.1536357. ISSN0094-243X.
^Vittorini-Orgeas, Alessandra; Bianconi, Antonio (2009-01-07). "From Majorana Theory of Atomic Autoionization to Feshbach Resonances in High Temperature Superconductors". Journal of Superconductivity and Novel Magnetism. 22 (3): 215–221. arXiv:0812.1551. doi:10.1007/s10948-008-0433-x. ISSN1557-1939. S2CID118439516.