Recent developments in classical density modification.
Recent developments in classical density modification.
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DOI：
10.1107/s090744490903947x
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发表时间：
2010-04
期刊：
影响因子：
--
通讯作者：
Cowtan K
中科院分区：
文献类型：
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作者：
Cowtan K
几种新的方法进行评估，用于在一个经典的密度修正计算的框架中的实验阶段的改进。这些方法已在一个新的计算机程序Parrot中实现。经典的密度修正技术（相对于统计方法）提供了一种计算成本低的方法，用于改善相位估计，以便为模型构建提供良好的电子密度图。统计方法的兴起导致了焦点从经典方法的转移;因此，最近的一些发展还没有进入经典的密度修改软件。本文介绍了一些最新的technologniques的应用，包括最重要的是使用的先验相位信息的相位误差的似然估计内的一个经典的密度修改框架。由此产生的软件提供了显着更好的结果比可比的经典方法，同时保持近两个数量级的速度比统计方法。
Several new methods are evaluated for use in the improvement of experimental phases in the framework of a classical density-modification calculation. These methods have been implemented in a new computer program, Parrot. Classical density-modification techniques (as opposed to statistical approaches) offer a computationally cheap method for improving phase estimates in order to provide a good electron-density map for model building. The rise of statistical methods has lead to a shift in focus away from the classical approaches; as a result, some recent developments have not made their way into classical density-modification software. This paper describes the application of some recent techniques, including most importantly the use of prior phase information in the likelihood estimation of phase errors within a classical density-modification framework. The resulting software gives significantly better results than comparable classical methods, while remaining nearly two orders of magnitude faster than statistical methods.