[phenixbb] Possible Twinned data

[Yuri]

Hello phenixers,
I am a little bit at loss since this is the first time I have 
encountered this situation.
I just collected preliminary data on a ligand soaked crystal. It goes 
to about 1.85 A. The centrics and acentrics reflections tests look a 
little deviant from ideal untwinned. I was looking at my xtriage log
file and it seemed to me like I have some twinned fraction. Phenix says 
not. I realize too my completeness is not good.
Any educated insight would be helpful as I have never dealt with 
twinning (if this actually the case).
Log file section:
Wilson ratio and moments

Acentric reflections
    <I^2>/<I>^2    :1.650   (untwinned: 2.000; perfect twin 1.500)
    <F>^2/<F^2>    :0.839   (untwinned: 0.785; perfect twin 0.885)
    <|E^2 - 1|>    :0.649   (untwinned: 0.736; perfect twin 0.541)


Centric reflections
    <I^2>/<I>^2    :2.099   (untwinned: 3.000; perfect twin 2.000)
    <F>^2/<F^2>    :0.749   (untwinned: 0.637; perfect twin 0.785)
    <|E^2 - 1|>    :0.703   (untwinned: 0.968; perfect twin 0.736)



NZ test (0<=z<1) to detect twinning and possible translational NCS


-----------------------------------------------
|  Z  | Nac_obs | Nac_theo | Nc_obs | Nc_theo |
-----------------------------------------------
| 0.0 |   0.000 |    0.000 |  0.000 |   0.000 |
| 0.1 |   0.052 |    0.095 |  0.171 |   0.248 |
| 0.2 |   0.126 |    0.181 |  0.285 |   0.345 |
| 0.3 |   0.197 |    0.259 |  0.371 |   0.419 |
| 0.4 |   0.271 |    0.330 |  0.440 |   0.474 |
| 0.5 |   0.334 |    0.394 |  0.499 |   0.520 |
| 0.6 |   0.394 |    0.451 |  0.553 |   0.561 |
| 0.7 |   0.447 |    0.503 |  0.600 |   0.597 |
| 0.8 |   0.497 |    0.551 |  0.629 |   0.629 |
| 0.9 |   0.541 |    0.593 |  0.660 |   0.657 |
| 1.0 |   0.581 |    0.632 |  0.697 |   0.683 |
-----------------------------------------------
| Maximum deviation acentric      :  0.062    |
| Maximum deviation centric       :  0.078    |
|                                             |
| <NZ(obs)-NZ(twinned)>_acentric  : -0.050    |
| <NZ(obs)-NZ(twinned)>_centric   : -0.021    |
-----------------------------------------------


  L test for acentric data

  using difference vectors (dh,dk,dl) of the form:
(2hp,2kp,2lp)
   where hp, kp, and lp are random signed integers such that
   2 <= |dh| + |dk| + |dl| <= 8

   Mean |L|   :0.441  (untwinned: 0.500; perfect twin: 0.375)
   Mean  L^2  :0.270  (untwinned: 0.333; perfect twin: 0.200)

   The distribution of |L| values indicates a twin fraction of
   0.00. Note that this estimate is not as reliable as obtained
   via a Britton plot or H-test if twin laws are available.

Cheers,
-- 
Yuri Pompeu