Crystal structures of increasingly large molecules: meeting the challenges with CRYSTALS software.
Crystal structures of increasingly large molecules: meeting the challenges with CRYSTALS software.
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DOI：
10.1186/s13065-015-0105-4
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发表时间：
2015
影响因子：
--
通讯作者：
Thompson AL
中科院分区：
文献类型：
--
作者：
Parois P;Cooper RI;Thompson AL
单晶衍射所研究的分子的尺寸和复杂性逐年增长，导致结构确定过程中遇到的困难也随之增加。从结晶本身和样品处理，到结构解决和细化，讨论了较大分子引起的具体问题。在细化过程中，可以使用多种方法来处理 Crystals 软件中大型结构遇到的问题。氢原子既不能轻易找到，也不能自由提炼，但可以自动施加限制。特殊的散射因子可用于模拟复杂的无序。最后，化学信息可以以约束的形式包含在内，以帮助确定一个好的模型。多重共线性问题在大型结构的细化中更容易出现；在某种程度上，更精确和准确的算法可以提供帮助。此外，如果全局最小值定义不太明确，则更快的细化可以执行更多的循环，这是良好收敛的必要条件。 Crystals 中算法的效率已得到提高，有助于解决这些问题。因此，晶体结构变得越来越大，并且它们的复杂性也在增加。晶体最小二乘法精度和速度的最新发展正在帮助结构科学家更有效地处理更大的结构。
The size and complexity of molecules being studied by single crystal diffraction is growing year by year, resulting in an increase in the difficulties encountered during structure determination. From the crystallisation itself and sample handling, to structure solution and refinement, specific problems due to larger molecules are discussed. During refinement, several methods are available to deal with the problems encountered with large structures within the software Crystals. Hydrogens atoms can neither be found easily nor refined freely, but restraints can be applied automatically. Special scattering factors can be used to model complex disorder. Finally chemical information can be included in the form of restraints in order to help the determination of a good model. Multicollinearity problems are more likely in the refinement of large structures; to some extent more precise and accurate algorithms can help. Also, if the global minimum is less well defined, faster refinement enables more cycles to be carried out, a necessity for good convergence. The efficiency of the algorithms in Crystals have been increased to help address these issues. Thus, crystal structures are getting larger and their complexity is increasing. Recent developments in precision and speed during the least squares in Crystals is helping the structural scientist to deal with larger structures more efficiently.
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影响因子：
15
作者：
Kilah, Nathan L.;Wise, Matthew D.;Beer, Paul D.
通讯作者：
Beer, Paul D.
DOI：
10.1107/s0108768102003324
发表时间：
2002-06-01
影响因子：
1.9
作者：
Bruno, IJ;Cole, JC;Taylor, R
通讯作者：
Taylor, R
影响因子：
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作者：
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通讯作者：
Van De Geijn, Robert A.
影响因子：
3
作者：
Mueller, Peter
通讯作者：
Mueller, Peter
影响因子：
15
作者：
Davis, Nicola K. S.;Thompson, Amber L.;Anderson, Harry L.
通讯作者：
Anderson, Harry L.