On Jul 20, 2011, at 15:24 , Eric Germaneau wrote: > Well, I don't know about "common tangent" concept.
you should: it is basic thermodynamics. Some time ago I wrote something on phase transitions: pag.13-21 of http://www.fisica.uniud.it/~giannozz/Corsi/sissa02.pdf These lecture notes are not worth much, but given the confusion of ideas that emerges from this thread, they might be useful Paolo --- Paolo Giannozzi, Dept of Chemistry&Physics&Environment, Univ. Udine, via delle Scienze 208, 33100 Udine, Italy Phone +39-0432-558216, fax +39-0432-558222