Optimizing the input parameters for powder charge flipping
نویسندگان
چکیده
منابع مشابه
The charge flipping algorithm.
This paper summarizes the current state of charge flipping, a recently developed algorithm of ab initio structure determination. Its operation is based on the perturbation of large plateaus of low electron density but not directly on atomicity. Such a working principle radically differs from that of classical direct methods and offers complementary applications. The list of successful structure...
متن کاملAb initio phasing of X-ray powder diffraction patterns by charge flipping.
Determining crystal structures from powder X-ray diffraction data remains a challenging problem in materials science. By embedding a Le-Bail-like procedure within the recently discovered charge-flipping phasing algorithm, an extremely simple, fast and effective ab initio method has been developed to determine phases directly from indexed powder diffraction patterns. The algorithm solves the deg...
متن کاملThe charge-flipping algorithm in crystallography.
The charge-flipping algorithm (CFA) is a member of the diverse family of dual-space iterative phasing algorithms. These algorithms use alternating modifications in direct and reciprocal space to find a solution to the phase problem. The current state-of-the-art CFA is reviewed and it is put in the context of related dual-space algorithms with relevance for crystallography. The CFA has found app...
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A multivariate Gaussian input density achieves capacity for multiple-input multiple-output flat fading channels with additive white Gaussian noise and perfect receiver channel state information. Capacity computation for these channels reduces to the problem of finding the best input covariance matrix, and is in general a convex semi-definite program. This paper presents Kuhn-Tucker optimality c...
متن کامل3 Ab initio structure solution by charge flipping
In this paper we present an extremely simple structure solution method termed charge flipping. It works ab initio on high resolution x-ray diffraction data in the manner of Fourier recycling. The real space modification simply changes the sign of charge density below a threshold, while in reciprocal space the modification is the F obs map without any weighting. We test the algorithm using synth...
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ژورنال
عنوان ژورنال: Acta Crystallographica Section A Foundations of Crystallography
سال: 2011
ISSN: 0108-7673
DOI: 10.1107/s0108767311079773