View source for Optical resolution

<font color="blue">Pouvoir de résolution</font> (''Fr''). <font color="red">Bildauflösung</font> (''Ge''). <font color="black">Risoluzione angolare</font> (''It''). <font color="purple">分解能</font> (''Ja''). <font color="green">Resolución de imagen</font> (''Sp'').


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

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

where <math>\sigma_\mathrm{Patt}</math> is the standard deviation of the Gaussian function fitted to the Patterson origin peak, <math>\sigma_\mathrm{sph}</math> 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 <math>1/d_\mathrm{min}</math>, and <math>d_\mathrm{min}</math> is the nominal [[resolution]].

== History ==

The term was introduced into the protein structure determination literature by Vaguine, A. A., Richelle, J. and Wodak, S. J. [(1999).
[http://dx.doi.org/10.1107/S0907444998006684 ''Acta Cryst.'' D'''55''', 191-205]. ''SFCHECK: a unified set of procedures for evaluating the quality of macromolecular structure-factor data and their agreement with the atomic model''].

[[Category:Biological crystallography]]
[[Category:Structure determination]]