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Space group determination: Difference between revisions
→Space groups as combinations of symmetry elements
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! spacegroup <br> number <br> suggested by <br> CORRECT | ! spacegroup <br> number <br> suggested by <br> CORRECT | ||
! other possibilities | ! other possibilities | ||
! | ! alternative indexing <br> possible? | ||
! choosing among all spacegroup possibilities | |||
|- | |- | ||
| -1 || aP || 1 || - || | | -1 || aP || 1 ||-|||| | ||
|- | |- | ||
| 2m || mP || 3 || 4 || screw axis extinctions let you decide | | 2m || mP || 3 || 4 |||| screw axis extinctions let you decide | ||
|- | |- | ||
| 2m || mC || 5 || - || The [[pointless]] article discusses why I2 (mI) should not be used. | | 2m || mC || 5 || - |||| The [[pointless]] article discusses why I2 (mI) should not be used. | ||
|- | |- | ||
| mmm || oP || 16 || 17, 18, 19 || screw axis extinctions let you decide. The [[pointless]] article discusses why CCP4's 1017 (P2<sub>1</sub>22), 2017 (P22<sub>1</sub>2), 2018 (P2<sub>1</sub>22<sub>1</sub>) , 3018 (P22<sub>1</sub>2<sub>1</sub>) are not needed and should not be used. | | mmm || oP || 16 || 17, 18, 19 |||| screw axis extinctions let you decide. The [[pointless]] article discusses why CCP4's 1017 (P2<sub>1</sub>22), 2017 (P22<sub>1</sub>2), 2018 (P2<sub>1</sub>22<sub>1</sub>) , 3018 (P22<sub>1</sub>2<sub>1</sub>) are not needed and should not be used. | ||
|- | |- | ||
| mmm || oC || 21 || 20 || screw axis extinctions let you decide | | mmm || oC || 21 || 20 |||| screw axis extinctions let you decide | ||
|- | |- | ||
| mmm || oF || 22 || - || | | mmm || oF || 22 ||-|||| | ||
|- | |- | ||
| mmm || oI || 23 || 24 || screw axis extinctions do '''not''' let you decide because the I centering results in h+k+l=2n and the screw axis extinction 00l=2n is just a special case of that. 23/24 do '''not''' form an enantiomorphic, but a ''special'' pair (ITC A §3.5, p. 46 in the 1995 edition). | | mmm || oI || 23 || 24 |||| screw axis extinctions do '''not''' let you decide because the I centering results in h+k+l=2n and the screw axis extinction 00l=2n is just a special case of that. 23/24 do '''not''' form an enantiomorphic, but a ''special'' pair (ITC A §3.5, p. 46 in the 1995 edition). | ||
|- | |- | ||
| 4/m || tP || 75 || 76, 77, 78 || screw axis extinctions let you decide, except between 76/78 enantiomorphs | | 4/m || tP || 75 || 76, 77, 78 ||yes|| screw axis extinctions let you decide, except between 76/78 enantiomorphs | ||
|- | |- | ||
| 4/m || tI || 79 || 80 || screw axis extinctions let you decide | | 4/m || tI || 79 || 80 ||yes|| screw axis extinctions let you decide | ||
|- | |- | ||
| 4/mmm || tP || 89 || 90, 91, 92, 93, 94, 95, 96 || screw axis extinctions let you decide, except between 91/95 and 92/96 enantiomorphs | | 4/mmm || tP || 89 || 90, 91, 92, 93, 94, 95, 96 |||| screw axis extinctions let you decide, except between 91/95 and 92/96 enantiomorphs | ||
|- | |- | ||
| 4/mmm || tI || 97 || 98 || screw axis extinctions let you decide | | 4/mmm || tI || 97 || 98 |||| screw axis extinctions let you decide | ||
|- | |- | ||
| -3 || hP || 143 || 144, 145 || screw axis extinctions let you decide, except between 144/145 enantiomorphs | | -3 || hP || 143 || 144, 145 ||4 possibilities|| screw axis extinctions let you decide, except between 144/145 enantiomorphs | ||
|- | |- | ||
| -3 || hR || 146 || - || | | -3 || hR || 146 || - ||yes, and obverse/reverse|| | ||
|- | |- | ||
| -3/m || hP || 149 || 151, 153 || screw axis extinctions let you decide, except between 151/153 enantiomorphs. Note: the twofold goes along the diagonal between a and b. | | -3/m || hP || 149 || 151, 153 ||yes|| screw axis extinctions let you decide, except between 151/153 enantiomorphs. Note: the twofold goes along the diagonal between a and b. | ||
|- | |- | ||
| -3/m || hP || 150 || 152, 154 || screw axis extinctions let you decide, except between 152/154 enantiomorphs. Note: compared to previous line, the twofold goes along a. | | -3/m || hP || 150 || 152, 154 ||yes|| screw axis extinctions let you decide, except between 152/154 enantiomorphs. Note: compared to previous line, the twofold goes along a. | ||
|- | |- | ||
| -3/m || hR || 155 || - || | | -3/m || hR || 155 || - ||obverse/reverse|| | ||
|- | |- | ||
| 6/m || hP || 168 || 169, 170, 171, 172, 173 || screw axis extinctions let you decide, except between 169/170 and 171/172 enantiomorphs | | 6/m || hP || 168 || 169, 170, 171, 172, 173 ||yes|| screw axis extinctions let you decide, except between 169/170 and 171/172 enantiomorphs | ||
|- | |- | ||
| 6/mmm || hP || 177 || 178, 179, 180, 181, 182 || screw axis extinctions let you decide, except between 178/179 and 180/181 enantiomorphs | | 6/mmm || hP || 177 || 178, 179, 180, 181, 182 |||| screw axis extinctions let you decide, except between 178/179 and 180/181 enantiomorphs | ||
|- | |- | ||
| m-3 || cP || 195 || 198 || screw axis extinctions let you decide | | m-3 || cP || 195 || 198 ||yes|| screw axis extinctions let you decide | ||
|- | |- | ||
| m-3 || cF || 196 || - || | | m-3 || cF || 196 ||-||yes || | ||
|- | |- | ||
| m-3 || cI || 197 || 199 || screw axis extinctions do '''not''' let you decide because the I centering results in h+k+l=2n and the screw axis extinction 00l=2n is just a special case of that. 197/199 do '''not''' form an enantiomorphic, but a ''special'' pair (ITC A §3.5, p. 46 in the 1995 edition). | | m-3 || cI || 197 || 199 ||yes|| screw axis extinctions do '''not''' let you decide because the I centering results in h+k+l=2n and the screw axis extinction 00l=2n is just a special case of that. 197/199 do '''not''' form an enantiomorphic, but a ''special'' pair (ITC A §3.5, p. 46 in the 1995 edition). | ||
|- | |- | ||
| m-3m || cP || 207 || 208, 212, 213 || screw axis extinctions let you decide, except between 212/213 enantiomorphs | | m-3m || cP || 207 || 208, 212, 213 |||| screw axis extinctions let you decide, except between 212/213 enantiomorphs | ||
|- | |- | ||
| m-3m || cF || 209 || 210 || screw axis extinctions let you decide | | m-3m || cF || 209 || 210 |||| screw axis extinctions let you decide | ||
|- | |- | ||
| m-3m || cI || 211 || 214 || screw axis extinctions let you decide | | m-3m || cI || 211 || 214 |||| screw axis extinctions let you decide | ||
|- | |- | ||
|} | |} | ||