Data Item _phasing_MIR_der.R_cullis_anomalous
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General 
- Item name
- _phasing_MIR_der.R_cullis_anomalous
- Category name
- phasing_MIR_der
- Attribute name
- R_cullis_anomalous
- Required in PDB entries
- no
- Used in current PDB entries
- Yes, in about 0.001 % of entries
Item Description
Residual factor Rcullis,ano for anomalous reflections for this
derivative.
The Cullis R factor was originally defined only for centric
reflections. It is, however, also a useful statistical
measure for anomalous reflections, which is how it is used in
this data item.
This is tabulated for acentric terms. A value less than 1.0
means there is some contribution to the phasing from the
anomalous data.
sum |Fph+obsFph-obs - Fh+calc - Fh-calc|
Rcullis,ano = ------------------------------------------------
sum|Fph+obs - Fph-obs|
Fph+obs = the observed positive Friedel structure-factor
amplitude for the derivative
Fph-obs = the observed negative Friedel structure-factor
amplitude for the derivative
Fh+calc = the calculated positive Friedel structure-factor
amplitude from the heavy-atom model
Fh-calc = the calculated negative Friedel structure-factor
amplitude from the heavy-atom model
sum is taken over the specified reflections
Ref: Cullis, A. F., Muirhead, H., Perutz, M. F., Rossmann, M. G.
& North, A. C. T. (1961). Proc. R. Soc. London Ser. A,
265, 15-38.
Data Type 
- Data type code
- float
- Data type detail
- float item types are the subset of numbers that are the floating numbers.
- Primitive data type code
- numb
- Regular expression
- -?(([0-9]+)[.]?|([0-9]*[.][0-9]+))([(][0-9]+[)])?([eE][+-]?[0-9]+)?
Allowed Boundary Conditions
| Minimum Value | Maximum Value |
|---|---|
| 0.0 | +∞ |