Second example of twinning by reticular merohedry

The structure determination of the next example, an AlLiF cage, is not as straightforward (Hatop et al., 2001 Herbst-lrmer and Sheldrick, 2002). XPREP does not 

124456 Reflections read from file ret2.hkl mean (I/sigma) = 8.47 

Additionally the high value for (11) = 1.068 shows that there are a lot of weak or unobserved reflections. XPREP confirms the twinning with its obverse/reverse twin test  

Obverse/reverse test for trigonal/hexagonal lattice 

Mean I obv only 9.7, rev only 5.0, neither obv nor rev 0.1 Preparing dataset for refinement with BASF 0.342 and TWIN -1000-10001 Reflections absent for both components will be removed 

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