[cctbxbb] cctbx.miller problem

Graeme.Winter at diamond.ac.uk Graeme.Winter at diamond.ac.uk
Tue Dec 5 22:14:48 PST 2017


If you want to compute all possible Miller indices to a given resolution, for a unit cell, without considering symmetry something like this is what you need:

def generate_reflection_indices(uc, dmin):

  maxh, maxk, maxl = uc.max_miller_indices(dmin)

  indices = []

  for h in range(-maxh, maxh + 1):
    for k in range(-maxk, maxk + 1):
      for l in range(-maxl, maxl + 1):
        if h == 0 and k == 0 and l == 0:
          continue
        if uc.d((h, k, l)) < dmin:
          continue
        indices.append((h, k, l))

  return indices

This does however mean that systematically absent reflections will be included - you would need to also test this with the space group object

Cheers Graeme

On 6 Dec 2017, at 00:48, Haiguang Liu <haiguang.liu at gmail.com<mailto:haiguang.liu at gmail.com>> wrote:

Hi Peter,

Will the command ms.expand_to_P1() do the trick to generate all symmetry peaks?

Best,
Haiguang

On Wed, Dec 6, 2017 at 2:13 AM, Peter Zwart <PHZwart at lbl.gov<mailto:PHZwart at lbl.gov>> wrote:
Hi Xuanxuan,

This:


from cctbx import miller
import cctbx
from cctbx import crystal

ms = miller.build_set(
    crystal_symmetry=crystal.symmetry(
        space_group_symbol='Fd-3m',
        unit_cell=(5.4307,5.4307,5.4307,90.00,90.0,90.00)),
    anomalous_flag=False,
    d_min=0.4)

for hkl in ms.indices():
    print hkl

gives:

(0, 2, 2)
.
.
.
(1, 3, 3)

etc

2,2,0 is related by symmetry to 0,2,2

HTH-P


On 5 December 2017 at 01:01, 李选选 <lixx11 at csrc.ac.cn<mailto:lixx11 at csrc.ac.cn>> wrote:

Dear cctbx developers,

I’m Xuanxuan, and I’m using cctbx to develop a crystallography-related algorithm. Recently, I found there is something wrong when I use miller package to generate miller indices for given space group and unit cell parameters. Maybe it’s my mistake, or it’s a bug.

Here are some details. I just use the following code to generate a list of miller indices for a Fd-3m crystal.

ms = miller.build_set(
    crystal_symmetry=crystal.symmetry(
        space_group_symbol='Fd-3m',
        unit_cell=(5.4307,5.4307,5.4307,90.00,90.0,90.00)),
    anomalous_flag=False,
    d_min=0.4)

And I found some reflections are missing, like 220, 311, which should exist according to the reflection conditions listed in this page http://img.chem.ucl.ac.uk/sgp/large/227az2.htm.

Looking forward to your response.

Thanks,
Xuanxuan


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Molecular Biophysics and Integrated Bioimaging &
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