mfisch
The question was how to add a new space group "F2/m"
Alan's answer:
It’s quite easy to add a new setting.
For F2/m then first find the primitive version in SGCOM5.CPP which is P2/m (space group number 10).
P2/m has a file in the sg directory called P2OM.SG and part that file looks like:
xyzs
{
x, y, z
-x, y, -z
x, -y, z
-x, -y, -z
} 4
The computer adapted symbol for P2/m in sgcom5.cpp looks like:
10 MCI1A000P2B000 { p2/m = p12/m1 = 10 - p112/m - p2/m11 }
To add a line for F2/m then simply use:
230 MCI1A000P2B000 { F2/m }
This will produce a file called F2OM.SG and part of it looks like:
xyzs
{
x, y, z
-x, y, -z
x, -y, z
-x, -y, -z
' +(1/2, 1/2, 0) -------------------------
x+1/2, y+1/2, z
-x+1/2, y+1/2, -z
x+1/2, -y+1/2, z
-x+1/2, -y+1/2, -z
' +(1/2, 0, 1/2) -------------------------
x+1/2, y, z+1/2
-x+1/2, y, -z+1/2
x+1/2, -y, z+1/2
-x+1/2, -y, -z+1/2
' +(0, 1/2, 1/2) -------------------------
x, y+1/2, z+1/2
-x, y+1/2, -z+1/2
x, -y+1/2, z+1/2
-x, -y+1/2, -z+1/2
} 16
Note, I don’t know what space group number to put for F2/m so I put 230 and I put the line at the bottom of the file.
It’s up to the user to ensure the correct crystal system (ie. correct lattice parameter constraints).