Simple question about Space Group

Smythe

In the general-symmetry-space group table over to the right on the page below:
https://en.wikipedia.org/wiki/Mimetite

It states:

Space group: P63/m

What does the letter P indicate and also the subscript 3?

Thanks

Morbert

Smythe wrote: »

In the general-symmetry-space group table over to the right on the page below:
https://en.wikipedia.org/wiki/Mimetite

It states:

Space group: P63/m

What does the letter P indicate and also the subscript 3?

Thanks

I'm somewhat familiar with point groups, and this seems to be a similarly structured system of notation.

http://en.wikipedia.org/wiki/Hermann–Mauguin_notation#Space_groups

P stands for primitive, while 3 is the degree of translation associated with the screw axes.

Smythe

Thanks Morbert.

It appears from your link that the P indicates it is a primitive lattice. I'm not entirely sure yet though what the sub 3 means.

kc90

Smythe wrote: »

Thanks Morbert.

It appears from your link that the P indicates it is a primitive lattice. I'm not entirely sure yet though what the sub 3 means.

This might help: http://en.wikipedia.org/wiki/Screw_axis#Screw_axis_of_a_spatial_displacement

''a rotation by 360°/n about an axis, combined with a translation along the axis by a multiple of the distance of the translational symmetry, divided by n. This multiple is indicated by a subscript. So, 6_3 is a rotation of 60° combined with a translation of 1/2 of the lattice vector, implying that there is also 3-fold rotational symmetry about this axis.''