Patrizia Calaminici Karl Jug Andreas M. Köster Cécile Arbez-Gindre Constantinos G. Screttas Mechanism for large first hyperpolarizabilities of phosphonic acid stilbene derivatives. 291-297 2002 23 Journal of Computational Chemistry 2 http://dx.doi.org/10.1002/jcc.10006 db/journals/jcc/jcc23.html#CalaminiciJKAS02