NEWSYM

THE NEWSYM TEST

This is an alternative space group symmetry checking approach based on structure factors calculated from the input model.

This alternate approach can be useful to detect the 'real' symmetry for a model derived from poor (possibly twinned) data using the same algorithms used to determine the space group from extinctions in observed data (also used by SYSTEM-S).

Instructions

NEWSYM can be invoked either with a left-button-click on NEWSYM or with the keyboard instruction:

CALC NEWSYM

CALC NEWSYM 0.3

to change the allowed angular error to 0.3 from the default 0.2 Deg.

EXAMPLE

Following is the output of an example NEWSYM run. The input was a CIF-file.


:: TITL  shelxl                                                               
:: CELL    19.2160    9.6890   18.6810    90.000   102.919    90.000    3390.0
:: SPGR C2/c        
:: Resd =  1, Z =  4, C36 H46 In2 N4
:: Moiety_Formula C36 H46 In2 N4
:: Formula_Z =   4
:: SpaceGroup_Z =   8
:: Formula_Z' =    0.500

:: mu(MoKa) =        13.9 cm-1 =    1.39 mm-1

NEWSYM - Determine Symmetry from F(calc) data(Resol =  0.60) for:  shelx
================================================================================

Analysis of General Reflections for Bravais Centering

Nr Ex. Condition     < I/sig(I) >    Number of Refl   I/sigI             .T/F.
                    .True. .False.   .True.  .False.   Max.F.    H  K  L Ratio
==============================================================================
 1 E HKL:H+K=2N     482.01    0.00     6135        0     0.00    0  0  0  99.0

Possible 2-Fold Axes - 2-Axis Crit = 0.50, Exp. Error = 0.30 Deg., LATT = C
-------------------------------------------------------------------------------
                 Rows      Products       Angle Between Two Direct Axes 
Nr   D    N Direct  Recip Dot Delta   1    2    3    4    5    6    7    8    9
--------------------------------------------------------------------------------
 1  9.689 0  1 0 0  2 1 0  2 0.002    0.

==== Transformation Matrix: Input (a,b,c) to Conventional Cell(a', b', c') ==== 
===============================================================================
(a')   ( 1.00 0.00 0.00) (a)   (x')   ( 1.00 0.00 0.00) (x)   Metrically
(b') = ( 0.00 1.00 0.00) (b).  (y') = ( 0.00 1.00 0.00) (y).  monoclinic  
(c')   ( 0.00 0.00 1.00) (c)   (z')   ( 0.00 0.00 1.00) (z)   FOM: 0.002

                Latt     a       b       c     Alpha   Beta  Gamma      Volume
-------------------------------------------------------------------------------
Input Cell        C    19.216   9.689  18.681  90.00 102.92  90.00     3390.06
Reduc Cell        P     9.689  10.760  18.681  78.48  90.00  63.24     1694.96
Conv. Cell       mC    19.216   9.689  18.681  90.00 102.92  90.00     3390.06


Nr Ex. Condition     < I/sig(I) >    Number of Refl   I/sigI             .T/F.
                    .True. .False.   .True.  .False.   Max.F.    H  K  L Ratio
==============================================================================
 1 E HKL:H+K=2N     482.01    0.00     6135        0     0.00    0  0  0  99.0
 7 E 0KL:K=2N       647.04    0.00      190        0     0.00    0  0  0  99.0
10 E H0L:H=2N       929.20    0.00      199        0     0.00    0  0  0  99.0
11 E H0L:L=2N       929.20    0.00      199        0     0.00    0  0  0  99.0
12 E H0L:H+L=2N     929.20    0.00      199        0     0.00    0  0  0  99.0
15 E HK0:H+K=2N     536.69    0.00      380        0     0.00    0  0  0  99.0
16 E H00:H=2N      1475.70    0.00       22        0     0.00    0  0  0  99.0
17 E 0K0:K=2N       701.42    0.00       10        0     0.00    0  0  0  99.0
18 E 00L:L=2N      1209.73    0.00       10        0     0.00    0  0  0  99.0


Candidate Space Groups
======================

      L C N Name      #  AbsFreq StandSet.     R(av)%    N A/C-Prob
-------------------------------------------------------------------------------
SPGR  2 1 1 Cc        9   844  Cc       ABC      0.00  2752   39
SPGR  2 2 1 C2/c     15  5965  C2/c     ABC      0.00  2752   61

SYMMETRY TOOLS

PLATON HOMEPAGE

26-Sep-2001 A.L.Spek