Index

Protein Data Bank exchange dictionary (pdbx) version 1.0521

_pdbx_refine_component.density_ratio_main_chain

Definition:

   
      The density ratio is similar to the density index, but summation of the
      density for the group is used for calculation.

      The ratio of density is the summation of the (2Fobs-Fcal) electron 
      density values for the group of atoms divided by the average value
      for the structure. Low values (less than 0.4) of this ratio may be 
      problematic for the group.


      index = [Sum~i D(xi)]/<D>_all

      Where:
 
      D(xi) = (2*Fobs - Fcal)
      <D>_all is the average value of density for the structure.
         The summation is for all the atoms of group.

Type: float

Mandatory item: no

Category: pdbx_refine_component