Implement c-type cells in crystallography module#2756
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| """ | ||
| End-centered B type: k+l even | ||
| """ | ||
| return ((k + l) % 2 == 0) |
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end-centered lattice (B) :h + l = even
Source: https://geo.libretexts.org/Bookshelves/Geology/Mineralogy_(Perkins_et_al.)/12%3A_X-ray_Diffraction_and_Mineral_Analysis/12.01%3A_X-ray_Diffraction/12.1.04%3A_Extinctions
| """ | ||
| Rhombohedral type: h-k+l multiple of 3 | ||
| """ | ||
| return ((h - k + l) % 3 == 0) |
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Should it be more explicit as in -h+k+l=3n? International Tables for Crystallography, p 81. Figure 1.5.1.6. The obverse setting ... -h+k+l=3n. Or do you target the general reflection condition as h - k + l =3n (also in International Tables for Crystallography, p 81. Figure 1.5.1.6. )
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Indeed, it looks like the formula was wrong ...
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@kif: While A and B were indeed mixed up, I don't tink h - k + l =3n is really wrong. There seems to be a difference between obverse and reverse setting, obverse seems to be standard now and since 1952, but the reverse is also used sometimes, and this is then described by h - k + l =3n.
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The 3 end-centering types (A, B, C) were missing. Thanks for spotting the exchange between A&B configuration. Beside this, I moved the extinction rules from the |
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close #2755