Hi everybody
Orthorhombic space group (Numbered from 16 to 74) has five different kinds of
classes starting
with "P" "C" "A" "F" "I".
P such as 56.Pccn or 57.Pbcm
C such as 36.Cmc21 or 37.Ccc2
A such as 40.Ama2 or 41.Aba2
F such as 42.Fmm2 or 43.Fdd2
I such as 44.Imm2 or 45.Iba2
My question is about ibrav assignment to above space groups.
in manual we have:
========================
8 Orthorhombic P celldm(2)=b/a
celldm(3)=c/a
v1 = (a,0,0), v2 = (0,b,0), v3 = (0,0,c)
9 Orthorhombic base-centered(bco) celldm(2)=b/a
celldm(3)=c/a
v1 = (a/2, b/2,0), v2 = (-a/2,b/2,0), v3 = (0,0,c)
-9 as 9, alternate description
v1 = (a/2,-b/2,0), v2 = (a/2,-b/2,0), v3 = (0,0,c)
10 Orthorhombic face-centered celldm(2)=b/a
celldm(3)=c/a
v1 = (a/2,0,c/2), v2 = (a/2,b/2,0), v3 = (0,b/2,c/2)
11 Orthorhombic body-centered celldm(2)=b/a
celldm(3)=c/a
v1=(a/2,b/2,c/2), v2=(-a/2,b/2,c/2), v3=(-a/2,-b/2,c/2)
===========================
so, it is clear that ibrav for "P" is 8, for "I" is 11 (I am not sure), for "F"
is 10.
What about "C" and "A"?
Regards
David Foster
Ph.D. Student of Chemistry
