On Aug 21, 2012, at 16:39 , karan deep wrote: > Birch function used in this program is P(V) equation and for > istate=1 i.e birch 1st order > is actually a 3rd order Birch-Murnaghan equation of state as > mentioned in WIKIPEDIA > page
I took the so-called "Birch 1st and 2nd order" and "Keane" equations of state from some geophysics paper many years ago. Nobody has ever complained since (which doesn't mean much about their correctness, tough). I cannot check those papers now because I am away from my desk. Clearly these formulae do not look like those of Wikipedia, but I am not sure how many variants of Birch-Murnaghan equations of states exist, and how reliable is Wikipedia on this subject. People working in geophysics are kindly requested to comment P. --- Paolo Giannozzi, Dept of Chemistry&Physics&Environment, Univ. Udine, via delle Scienze 208, 33100 Udine, Italy Phone +39-0432-558216, fax +39-0432-558222