On Jun 25, 2011, at 23:39 , Abolore Musari wrote: > alpha equal beta equal 90 degree
beta = 90 ... > beta was gotten from reitveld refinement to be 113.81 ...or beta = 113.81? > i dont know if my celldm(4) which is equal to cos(ab) should > be cos90 or cos113.81 or tell me the appropriate way to get > celldm(4)=cos(ab). the monoclinic (P? ibrav=12?) lattice can be described with unique (i.e. orthogonal to a) axis c, b axis at angle gamma /= 90 with a; or with unique axis b, c axis at angle beta /= 90 with a. QE uses the former description; apparently you have found the latter description in the literature, so you have to either convert the latter into the former, or write down explicitly the crystal axis, or to use the latest svn version that allows for the latter description as well (ibrav=-12) 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
