Dear Jiayu, The lattice vectors of a fcc crystal are taken as a_1=a/2(i+j) etc. So the volume |a_1.(a_2 x a_3)| will turn out to be 1/4(a^3) rather than a^3.
-Mighfar Imam JNCASR, B'lore, India. > Dear all users, > > When i performed the vc-relax calculation, i > found the "unit-cell volume" in the > output file is not the volume of the supercell i > used. I also found it is the same > in the SCF calculation. For example, in SCF > calculation, my input lattice ibrav =2 > (.ie., fcc), celldm(1)=10.6920, then the output > parameters are: > > lattice parameter (a_0) = 10.6920 a.u. > -------a > unit-cell volume = 305.5743 > -------omega > > You can see omega is not the cubic of a. Then, > how the volume "omega" in the code > is calculated here? Is it included in the > cell_base.f90 file? > > Thanks a lot. > > Jiayu > > > > > ------------------------------ > ------------------------------------------- > Jiayu Dai > Department of Physics > National University of Defense Technology, > Changsha, 410073, P R China > ----------------------------------------- > _______________________________________________ > Pw_forum mailing list > Pw_forum at pwscf.org > http://www.democritos.it/mailman/listinfo/pw_forum >
