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1、Shelx单晶结构解析 常见问题分析,报告人：赵丹 E-mail: 2016.6.14,报告内容 一、无序 二、双晶 三、非周期结构 四、小结,分类： 1、Positional disorder 对于复杂的位置无序，考虑收录低温数据，可能消除无序。 2、Substitutional disorder 对于占有率无序，最好在实验设计时予以避免。,一、无序（Disorder）,1、位置无序的精修,简单无序 EADP C1 C1 FVAR 0.11272 0.6 C1 1 0.255905 0.173582 -0.001344 21.00 0.05 C1 1 0.299373 0.178166 -
2、0.015708 -21.00 0.05,FVAR 0.234 0.6 PART 1 21.0000 AFIX 66 C3A 1 0.6433 0.2938 0.1109 11.0 0.06836 C4A 1 0.6218 0.2673 0.2408 11.0 0.05727 C5A 1 0.5976 0.3191 0.3424 11.0 0.06729 C6A 1 0 0 0 11.00000 0.05 C1A 1 0 0 0 11.00000 0.05 C2A 1 0 0 0 11.00000 0.05 AFIX 0 PART 2 -21.0000 AFIX 66 C3B 1 0.6322
3、 0.2673 0.1320 11.00000 0.06836 C4B 1 0.6118 0.2471 0.2666 11.00000 0.05727 C5B 1 0.5976 0.3191 0.3424 11.00000 0.06729 C6B 1 0 0 0 11.00000 0.05 C1B 1 0 0 0 11.00000 0.05 C2B 1 0 0 0 11.00000 0.05 AFIX 0 PART 0,刚性基团 苯环无序,2、占位无序的处理,精修命令： EADP Al1 Ti1 EXYZ Al1 Ti1 FVAR 0.2 0.5 Al1 21.00 0.05 Ti1 -21.
4、00 0.05,双晶的概念 定义：由两个（或多个）互不平行的同种单体，彼此间按一定的对称关系相互取向而组成的规则连生晶体。,二、双晶（孪晶，Twin）,石膏燕尾双晶,萤石贯穿双晶,石英接触双晶（I）,石英接触双晶（II）,简单双晶,聚片双晶,赝六次轴双晶,寄生双晶,多重双晶,异种晶体的连生(类似于双晶),磁铁矿小晶体浮生于赤铁矿表面,双晶的类别,TLS twin: Twin Lattice Symmetry TLQS twin: Twin Lattice Quasi-Symmetry,Refinement of Twinned Structures with SHELXL97,where o.
5、s.f. is the overall scale factor, km is the fractional contribution of twin domain m, Fcm is the calculated structure factor of twin domain m and n is the number of twin domains.,R. Herbst-Irmer, G. M. Sheldrick, Acta Cryst. (1998). B54, 443-449.,文石 Aragonite 双晶面,双晶要素（Twin law）,1、Racemic twin (inver
6、sion twin ),The twin operator belongs to the Laue group but not to the point group of the crystal. Example: Iding et al., Tetrahedron asymmetry 14 (2003) 1541-1545.,TWIN BASF 0.5,2、Merohedral twin,Twin element belongs to the point group of the lattice but not to the point group of the crystal. 很多缺面双
7、晶都是Perfect twin，即两种双晶组分比为1 ：1。大部分三方、六方晶系的双晶都是这种情况。,Perfect twin,Acta Cryst. (2003). D59, 1995,Merohedral Twin example 1：,NaGe2P3O12： （Journal of Molecular Structure 922 (2009) 127134） 数据收录：Saturn70 (4x4 bin mode) _cell_length_a 8.1087(30) _cell_length_b 8.1087(30) _cell_length_c 21.5360(82) _cell_an
8、gle_alpha 90.0000(0) _cell_angle_beta 90.0000(0) _cell_angle_gamma 120.0000(0) _cell_volume 1226.3040(0) _cell_formula_units_Z 18 _cell_measurement_temperature 294.1500 _cell_measurement_reflns_used 1317 _cell_measurement_theta_min 2.8373 _cell_measurement_theta_max 27.4333 _symmetry_space_group_nam
9、e_H-M R3(h),TWIN 0 1 0 1 0 0 0 0 -1 BASF 0.446,XPREP,3、Pseudo-Merohedral Twin,The twin element belongs to the higher crystal system. Common examples are a monoclinic with b90.0or orthorhombic with a c Pseudo-Merohedral Twin example 1： CELL 0.71073 8.9643 30.5390 8.9625 90.000 90.000 90.000 ZERR8.000
10、0 0.0011 0.0060 0.0012 0.000 0.000 0.000 特点： a c，四方晶系R(sym)值只高一点。,四方：解不出来 正交Ibca空间群，R1值降不下去。,TWIN 0 0 1 0 -1 0 1 0 0 BASF 0.53,Pseudo-Merohedral Twin example 2： Zn(C9NH7)2(SCN)2 Monoclinic，P 2/n a = 21.412(5)， b = 4.9745(11)， c = 21.424(5)，=119.436(6) 特点：a c， 120,Final R indices (gt)：R1=0.0479,Examp
11、le 3: Pseudo six-fold twin K2SO4:,直接法解结构失败,真实结构： Pnma CELL 0.71073 7.4730 5.7880 10.0320 90.000 90.000 90.000 TWIN law: (-1 0 0 0 0.5 0.5 0 1.5 -0.5) (-1 0 0 0 -0.5 0.5 0 1.5 0.5) BASF 0.35 0.25 _refine_ls_R_factor_all 0.0325 _refine_ls_R_factor_gt 0.0297 _refine_ls_wR_factor_ref 0.0921 _refine_ls_w
12、R_factor_gt 0.0904 _refine_ls_goodness_of_fit_ref 1.236 _refine_ls_restrained_S_all 1.236 _refine_ls_shift/su_max 0.000 _refine_ls_shift/su_mean 0.000,4、Non-merohedral twin The twin operation does not belong to the Laue group or to the point group of the crystal. 双晶轴往往属于比实际晶胞更大的超晶胞，直接指标化会将晶胞定大！,Non-
13、merohedral twin example 1: 如某正交晶系： 晶胞参数a=7.02， b=13.98， c=16.66 由于2a b 形成了一个晶胞体积扩大2倍的赝四方晶胞: a=14.01， b=14.01， c=16.67,a = -0.5b, b = 2a, c = c,Non-merohedral twin example 2: Pb(C12H6O4): monoclinic, P21/c a = 13.1648(18), b = 5.3881(8), c = 14.599(2) , = 95.759(2), R = 0.043 and wR = 0.097.,Twin law
14、 (1 0 0 0 1 0 0.224 0 1),BASF 0.26394 HKLF 5,_refine_ls_R_factor_all 0.0672 _refine_ls_R_factor_gt 0.0431 _refine_ls_wR_factor_ref 0.0972 _refine_ls_wR_factor_gt 0.0880 _refine_ls_goodness_of_fit_ref 1.007 _refine_ls_restrained_S_all 1.007 _refine_ls_shift/su_max 0.000 _refine_ls_shift/su_mean 0.000
15、,5、Reticular pseudo-merohedral (Chameleon) twin,RbFeO2：Orthorhombic, Pbca a=5.7568 (7), b=11.5136 (13), c=16.2827 (18) RF2 2(F2)= 0.053, wR(F2)=0.126, S=1.17,Jurgen Nuss, Naveed Zafar Ali, Martin Jansen, Acta Cryst. (2007). B63, 719725,异常的系统消光,Twin matrix,三、Aperiodic crystal,分类： 1. 有/无公度调制结构（in/commensurate modulated structure） 有公度调制结构即超结构（super structure） 2. 复合结构（composite structure） 3. 准晶体（quasi crystal） 非周期结构在配位聚合物中很少见，而且以超结构居多。,1. Incommensurate modulated structure,Incommensurate modulated structures have an average three-d
