[phenixbb] Space group

[mohamed noor]

Dear all

I processed my images in point group P 3 2 1. After running Phaser and
building it, the space group was P 3(2) 2 1. However, the refinement is
stuck with Rfree at around 35-38 % (data extending to 3.3 A). As I believe
the R factor is a bit high, and I have a different crystal form in P4(2)
2(1) 2 with R free at 25 % for data to 3.8 A, I expanded it to P 1, redid
Phaser searching for 48 copies. After refinement, the R free is at 38 %.

For some reason, Zanuda/Refmac is not able to read my files. So I ran
Xtriage instead:

A summary of R values for various possible point groups follow.


-------------------------------------------------------------------------------------------------------
  | Point group          | mean R_used | max R_used | mean R_unused | min
R_unused | BIC       | choice |

-------------------------------------------------------------------------------------------------------
  | P 3                  | 0.000       | 0.000      | 0.271         |
0.000        | 3.521e+05 |        |
  | C 1 2 1 (2*y,-x+y,z) | 0.423       | 0.423      | 0.200         |
0.000        | 1.763e+06 |        |
  | P 1                  |  None       |  None      | 0.219         |
0.000        | 1.056e+06 |        |
  | P 6                  | 0.242       | 0.423      | 0.200         |
0.000        | 1.365e+06 |        |
  | C 2 2 2 (x+y,2*y,z)  | 0.271       | 0.423      | 0.200         |
0.000        | 1.464e+06 |        |
  | P 3 2 1              | 0.000       | 0.000      | 0.423         |
0.423        | 1.761e+05 |        |
  | P 3 1 2              | 0.242       | 0.423      | 0.200         |
0.000        | 1.365e+06 |        |
  | C 2 2 2 (2*x,x+y,z)  | 0.271       | 0.423      | 0.200         |
0.000        | 1.464e+06 |        |
  | P 1 1 2              | 0.423       | 0.423      | 0.200         |
0.000        | 1.763e+06 |        |
  | P 6 2 2              | 0.219       | 0.423      |  None         |
None        | 1.265e+06 |        |
  | C 1 2 1 (x+y,-x+y,z) | 0.000       | 0.000      | 0.242         |
0.000        | 5.282e+05 |        |
  | C 1 2 1 (x+y,2*y,z)  | 0.423       | 0.423      | 0.200         |
0.000        | 1.763e+06 |        |
  | C 1 2 1 (x-y,2*x,z)  | 0.000       | 0.000      | 0.242         |
0.000        | 5.282e+05 |        |
  | C 2 2 2 (x-y,x+y,z)  | 0.271       | 0.423      | 0.200         |
0.000        | 1.464e+06 |        |
  | C 1 2 1 (2*x,x+y,z)  | 0.000       | 0.000      | 0.242         |
0.000        | 5.282e+05 |        |
  | C 1 2 1 (x-y,x+y,z)  | 0.423       | 0.423      | 0.200         |
0.000        | 1.763e+06 |        |

-------------------------------------------------------------------------------------------------------

R_used: mean and maximum R value for symmetry operators *used* in this
point group
R_unused: mean and minimum R value for symmetry operators *not used* in
this point group

Looking at the R values, it is possible that it is actually C 1 2 1.

My questions:

1. What is the difference between the C 1 2 1 lines? What do the values in
brackets mean?

2. Since Xtriage did indicate a possible NCS axis parallel to
crystallographic axis (and it looks almost like that in my P321 model), do
I reintegrate in one of those C121 and then redo Phaser/refinement? I can
post a screenshot of model if that will help.

Thanks.
Mohamed
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