Solution X-ray Scattering Form-Factors with Arbitrary Electron Density Profiles and Polydispersity Distributions

2015 ◽  
Vol 56 (8) ◽  
pp. 622-628 ◽  
Author(s):  
Tal Ben-Nun ◽  
Roi Asor ◽  
Avi Ginsburg ◽  
Uri Raviv
Keyword(s):  
Electron Density ◽  
Form Factors ◽  
Density Profiles ◽  
X Ray ◽  
X Ray Scattering ◽  
Electron Density Profiles ◽  
Ray Scattering

scholarly journals DiSCaMB: a software library for aspherical atom model X-ray scattering factor calculations with CPUs and GPUs

2018 ◽  
Vol 51 (1) ◽  
pp. 193-199 ◽  
Author(s):  
Michał L. Chodkiewicz ◽  
Szymon Migacz ◽  
Witold Rudnicki ◽  
Anna Makal ◽  
Jarosław A. Kalinowski ◽  
...  
Keyword(s):  
Electron Density ◽  
Graphics Processing Units ◽  
Structural Parameters ◽  
Structure Refinement ◽  
Form Factors ◽  
Density Model ◽  
X Ray ◽  
X Ray Scattering ◽  
Scattering Factor ◽  
Ray Scattering

It has been recently established that the accuracy of structural parameters from X-ray refinement of crystal structures can be improved by using a bank of aspherical pseudoatoms instead of the classical spherical model of atomic form factors. This comes, however, at the cost of increased complexity of the underlying calculations. In order to facilitate the adoption of this more advanced electron density model by the broader community of crystallographers, a new software implementation calledDiSCaMB, `densities in structural chemistry and molecular biology', has been developed. It addresses the challenge of providing for high performance on modern computing architectures. With parallelization options for both multi-core processors and graphics processing units (using CUDA), the library features calculation of X-ray scattering factors and their derivatives with respect to structural parameters, gives access to intermediate steps of the scattering factor calculations (thus allowing for experimentation with modifications of the underlying electron density model), and provides tools for basic structural crystallographic operations. Permissively (MIT) licensed,DiSCaMBis an open-source C++ library that can be embedded in both academic and commercial tools for X-ray structure refinement.

scholarly journals Exploiting the full quantum crystallography

2018 ◽  
Vol 96 (7) ◽  
pp. 599-605 ◽  
Author(s):  
Lou Massa ◽  
Chérif F. Matta
Keyword(s):  
Quantum Mechanics ◽  
Electron Density ◽  
Mathematical Structure ◽  
Scattering Data ◽  
X Ray ◽  
X Ray Crystallography ◽  
X Ray Scattering ◽  
Fundamental Value ◽  
Quantum Crystallography ◽  
Ray Scattering

Quantum crystallography (QCr) is a branch of crystallography aimed at obtaining the complete quantum mechanics of a crystal given its X-ray scattering data. The fundamental value of obtaining an electron density matrix that is N-representable is that it ensures consistency with an underlying properly antisymmetrized wavefunction, a requirement of quantum mechanical validity. However, X-ray crystallography has progressed in an impressive way for decades based only upon the electron density obtained from the X-ray scattering data without the imposition of the mathematical structure of quantum mechanics. Therefore, one may perhaps ask regarding N-representability “why bother?” It is the purpose of this article to answer such a question by succinctly describing the advantage that is opened by QCr.

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