Dear Steve,

On which base should I set my a1 & a2 & a3 for building a non-ideal hcp by lattice custom? for hcp there is:

a1 = 1 0 0, a2 = 0 sqrt(3) 0, and a3 = 0 0 sqrt(8/3) .

when sqrt(8/3)=1.63 belongs to the c/a ratio of an ideal hcp. So to set a non-ideal hcp by the lattice custom command, should I use my specific c/a which is equal to 1.58 instead of sqrt(8/3)? moreover, is sqrt(3)=1.73 a fixed value for a2 in all non-ideal fcc beacase of the only one degree of freedom for hcp?

I have a=2.95 , c=4.68 , c/a=1.58, could you tell me whether or not it is true?

lattice custom 1 a1 2.97 0.0 0.0 a2 0.0 1.73 0.0 a3 0.0 0.0 1.58 &

basis 0.0 0.0 0.0 basis 0.5 0.5 0.0 basis 0.5 0.25 0.5 basis 0.0 0.75 0.5

Thank you,

Nazanin