Re: Generating space group general positions - issues implementing Shmueli (1984)

2022-11-08 Thread reinhard.neder
Hi Matthew, I am glad to hear my answer helped. Yes, Giacovazzo is a good read. The detail on the order of a rotoinversion is correct, I had forgotten that. Fd-3c should have five + two generators: (as used in the International Tables) (the identity operation ) a two-fold (screw-)axis

Re: Generating space group general positions - issues implementing Shmueli (1984)

2022-11-08 Thread Matthew Rowles
Thanks for that Reinhard. The order of the -3 operation being 6 was the key to fix all (most) of my problems. I'll probably implement the augmented matrix methodology in my code, as it looks like it simplifies keeping track of the translation vector. I've also just reserved my library's copy of

Re: Generating space group general positions - issues implementing Shmueli (1984)

2022-11-08 Thread Reinhard Neder
Hi Matthew, Your initial description of the symmetry operations and their multiplication is just fine. Your error is at the assumption that the triple application of a 3bar rotation is the unit matrix. The 3bar operation ( you call it 3Q) is the combination of the 3-fold rotation with a

Abstracts by 21 Nov for the 2023 IUCr Congress in Melbourne (https://iucr2023.org)

2022-11-08 Thread Alan W Hewat
Posted at the request of Prof. Sudhindra Rayaprol, IUCr Commission on Magnetic Structures (http://magcryst.org) Dear Colleagues, The upcoming 2023 IUCr Congress in Melbourne (https://iucr2023.org) will be an exciting event for all researchers involved in the determination and application of