P1 (space group) From Wikipedia, the free encyclopedia P1 may refer to either of the following space groups in three dimensions: P1, space group no. 1 P1, space group no. 2 Index of articles associated with the same name This set index article includes a list of related items that share the same name (or similar names). If an internal link incorrectly led you here, you may wish to change the link to point directly to the intended article. Related Articles