Optimal local axes and symmetry assignment for charge-density refinement
Optimal local axes and symmetry assignment for charge-density refinement
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DOI：
10.1107/s0021889808033384
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发表时间：
2008-12-01
影响因子：
6.1
通讯作者：
Jelsch, Christian
中科院分区：
文献类型：
--
作者：
Domagala, Slawomir;Jelsch, Christian
从建立基于多极模型的常见化学原子类型的扩展电子密度库的角度出发，提出了新的一致局域轴系统。因此，最佳对称性约束可以应用于原子和大量的多极人口可以固定为零值。在小化合物的多极细化中引入对称性约束，可以减少存储在库中的多极参数的数量，并需要用于描述原子电子密度。在不应用对称约束的细化中，使用最佳轴使得能够突出显示与局部伪对称的偏差。当轴与原子的局部几何形状一致时，对称性约束或多极约束的应用更有效，并且可以导致改进的晶体学无R残差。新的局域轴系统，基于两个或三个原子邻居，也可以有效地应用于过渡金属配合物的描述。(C)2008年国际结晶学联合会在新加坡印刷-版权所有
In the perspective of building an expanded electron-density library based on multipolar modelling for common chemical atom types, new consistent local axes systems are proposed. Optimal symmetry constraints can consequently be applied to atoms and a large number of multipole populations can be fixed to a zero value. The introduction of symmetry constraints in the multipolar refinement of small compounds allows a reduction in the number of multipolar parameters stored in the library and required for the description of the atomic electron density. In a refinement where the symmetry constraints are not applied, the use of optimal axes enables the deviations from the local pseudo-symmetry to be highlighted. The application of symmetry constraints or restraints on multipoles is more effective when the axes are in accordance with the local geometry of the atom and can lead to improved crystallographic R-free residuals. The new local axes systems, based on two or three atom neighbours, can also be usefully applied to the description of transition metal complexes. (C) 2008 International Union of Crystallography Printed in Singapore - all rights reserved