Invarioms are aspherical atomic scattering factors that enable structure refinement of more accurate and more precise geometries than refinements with the conventional independent atom model (IAM). The use of single-crystal X-ray diffraction data of a resolution better than sin θ/λ = 0.6 Å−1 (or d = 0.83 Å) is recommended. The invariom scattering-factor database contains transferable pseudoatom parameters of the Hansen–Coppens multipole model and associated local atomic coordinate systems. Parameters were derived from geometry optimizations of suitable model compounds, whose IUPAC names are also contained in the database. Correct scattering-factor assignment and orientation reproduces molecular electron density to a good approximation. Molecular properties can hence be derived directly from the electron-density model. Coverage of chemical environments in the invariom database has been extended from the original amino acids, proteins and nucleic acid structures to many other environments encountered in organic chemistry. With over 2750 entries it now covers a wide sample of general organic chemistry involving the elements H, C, N and O, and to a lesser extent F, Si, S, P and Cl. With respect to the earlier version of the database, the main modification concerns scattering-factor notation. Modifications improve ease of use and success rates of automatic geometry-based scattering-factor assignment, especially in condensed hetero-aromatic ring systems, making the approach well suited to replace the IAM for structures of organic molecules.

B. Dittrich

C. B. Hübschle

K. Pröpper

F. Dietrich

T. Stolper

J. J. Holstein

Acta Crystallographica Section B Structural Science

Acta Crystallographica Section B: Structural Science, Crystal Engineering and Materials publishes scientific articles related to the structural science of compounds and materials in the widest sense. Knowledge of the arrangements of atoms, including their temporal variations and dependencies on temperature and pressure, is often the key to understanding physical and chemical phenomena and is crucial for the design of new materials and supramolecular devices. Acta Crystallographica B is the forum for the publication of such contributions. Scientific developments based on experimental studies as well as those based on theoretical approaches, including crystal-structure prediction, structure-property relations and the use of databases of crystal structures, are published.

Acta Crystallographica Section B: Structural Science, Crystal Engineering and Materials publishes scientific articles related to the structural science of compounds and materials in a broad sense. Understanding the arrangements of atoms, including their temporal variations and dependencies on temperature and pressure, is often key to grasping physical and chemical phenomena and is crucial for the design of new materials and supramolecular devices. Acta Crystallographica B serves as a forum for the publication of such contributions. The journal welcomes scientific developments based on both experimental studies and theoretical approaches, including crystal-structure prediction, structure-property relations, and the utilization of databases of crystal structures.

《Acta Crystallographica Section B: Structural Science, Crystal Engineering and Materials》期刊发表与化合物和材料的结构科学相关的科学文章。原子排列的知识，包括其时间变化及对温度和压力的依赖，通常是理解物理和化学现象的关键，并且对新材料和超分子器件的设计至关重要。《Acta Crystallographica B》是发表此类贡献的论坛。期刊接受基于实验研究的科学发展以及基于理论方法的研究，包括晶体结构预测、结构-性质关系和晶体结构数据库的使用。

The generalized invariom database (GID)

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