[missUK11]

For the space group P2₁cn, I understand that there is a 2-fold screw axis which consists of a 180° rotation followed by a translation of 1/2 unit length, but how do I know along what direction ( a, b or c) the translation occurs. Also what does does the c and n mean?

please someone help me

[kriggy]

My knowledge on this topic is very limited but I think the translation goes along the rotation axis

[missUK11]

My knowledge on this topic is very limited but I think the translation goes along the rotation axis

ok thanks!

[AWK]

This is a non-standard setting of orthorhombic space group _Pna2₁. A sequence of symbols in orthorhombic space group 2₁, _c, and _n concern always a, b and c direction, respectively. For axes moving is always along direction of axis, for planes a, b ,c, d, and n direction of moving and translation is coded by the symbol (read textbook).

[missUK11]

This is a non-standard setting of orthorhombic space group _Pna2₁. A sequence of symbols in orthorhombic space group 2₁, _c, and _n concern always a, b and c direction, respectively. For axes moving is always along direction of axis, for planes a, b ,c, d, and n direction of moving and translation is coded by the symbol (read textbook).

Thank-you