Optical resolution

Pouvoir de résolution (Fr);　Bildauflösung (Ｇｅ); Resolución de imagen (Ｓｐ); Risoluzione angolare (It); 分解能 (Ja).

By analogy with optical observations, e.g. in astronomy, the term optical resolution in structure determination, $d_\mathrm{opt}$, is used to describe the expected minimum distance between two resolved peaks in an electron-density map.

$d_\mathrm{opt} = [2(\sigma_\mathrm{Patt}^2 + \sigma_\mathrm{sph}^2)]^{1/2}$

where $\sigma_\mathrm{Patt}$ is the standard deviation of the Gaussian function fitted to the Patterson origin peak, $\sigma_\mathrm{sph}$ is the standard deviation of the Gaussian function fitted to the origin peak of the spherical interference function, representing the Fourier transform of a sphere with radius $1/d_\mathrm{min}$, and $d_\mathrm{min}$ is the nominal resolution.

History

The term was introduced into the protein structure determination literature by Vaguine, A. A., Richelle, J. & Wodak, S. J. [(1999). Acta Cryst. D55, 191-205. SFCHECK: a unified set of procedures for evaluating the quality of macromolecular structure-factor data and their agreement with the atomic model].