XmlmmCIF equivalent: phasing_MIR_der Data items in the PHASING_MIR_DER category record details about individual derivatives used in the phasing of the structure when methods involving isomorphous replacement are involved. A derivative in this context does not necessarily equate with a data set; for instance, the same data set could be used to one resolution limit as an isomorphous scatterer and to a different resolution (and with a different sigma cutoff) as an anomalous scatterer. These would be treated as two distinct derivatives, although both derivatives would point to the same data sets via _phasing_MIR_der.der_set_id and _phasing_MIR_der.native_set_id. XmlmmCIF equivalent: phasing_MIR_der/R_cullis_acentric Residual factor R~cullis,acen~ for acentric reflections in this derivative. The Cullis R factor was originally defined only for centric reflections. It is, however, also a useful statistical measure for acentric reflections, which is how it is used in this data item. sum| |Fph~obs~ +/- Fp~obs~| - Fh~calc~ | R~cullis,acen~ = -------------------------------------------------------------- sum|Fph~obs~ - Fp~obs~| Fp~obs~ = the observed structure factor amplitude of the native Fph~obs~ = the observed structure factor amplitude of the derivative Fh~calc~ = the calculated 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. Roy. Soc. A265, 15-38. XmlmmCIF equivalent: phasing_MIR_der/R_cullis_anomalous Residual factor R~cullis,ano~ for anomalous reflections in 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. Any value <1.0 means there is some contribution to the phasing from the anomalous data. sum| |Fph+~obs~Fph-~obs~ - Fh+~calc~ - Fh-~calc~| | R~cullis,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. Roy. Soc. A265, 15-38. XmlmmCIF equivalent: phasing_MIR_der/R_cullis_centric Residual factor R~cullis~ for centric reflections in this derivative. sum| |Fph~obs~ +/- Fp~obs~| - Fh~calc~ | R~cullis~ = ---------------------------------------------------------------- sum|Fph~obs~ - Fp~obs~| Fp~obs~ = the observed structure factor amplitude of the native Fph~obs~ = the observed structure factor amplitude of the derivative Fh~calc~ = the calculated 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. Roy. Soc. A265, 15-38. XmlmmCIF equivalent: phasing_MIR_der/d_res_high The highest resolution for the interplanar spacing in the reflection data used for this derivative. This is the smallest d value. XmlmmCIF equivalent: phasing_MIR_der/d_res_low The lowest resolution for the interplanar spacing in the reflection data used for this derivative. This is the highest d value. XmlmmCIF equivalent: phasing_MIR_der/der_set_id The data set that was treated as the derivative in this experiment. This data item is a pointer to _phasing_set.id in the PHASING_SET category. XmlmmCIF equivalent: phasing_MIR_der/details A description of special aspects of this derivative, its data, its solution, or its use in phasing. XmlmmCIF equivalent: phasing_MIR_der/native_set_id The data set that was treated as the native in this experiment. This data item is a pointer to _phasing_set.id in the PHASING_SET category. XmlmmCIF equivalent: phasing_MIR_der/number_of_sites The number of heavy atom sites in this derivative. XmlmmCIF equivalent: phasing_MIR_der/power_acentric The mean phasing power P for acentric reflections in this derivative. sum|Fh~calc~^2^| P = (------------------------------------------------)^1/2^ sum|Fph~obs~ - Fph~calc~|^2^ Fph~obs~ = the observed structure factor amplitude of this derivative Fph~calc~ = the calculated structure factor amplitude of this derivative Fh~calc~ = the calculated structure factor amplitude from the heavy atom model sum is taken over the specified reflections XmlmmCIF equivalent: phasing_MIR_der/power_centric The mean phasing power P for centric reflections in this derivative. sum|Fh~calc~^2^| P = (-----------------------------------------------)^1/2^ sum|Fph~obs~ - Fph~calc~|^2^ Fph~obs~ = the observed structure factor amplitude of the derivative Fph~calc~ = the calculated structure factor amplitude of the derivative Fh~calc~ = the calculated structure factor amplitude from the heavy atom model sum is taken over the specified reflections XmlmmCIF equivalent: phasing_MIR_der/reflns_acentric The number of acentric reflections used in phasing for this derivative. XmlmmCIF equivalent: phasing_MIR_der/reflns_anomalous The number of anomalous reflections used in phasing for this derivative. XmlmmCIF equivalent: phasing_MIR_der/reflns_centric The number of centric reflections used in phasing for this derivative. XmlmmCIF equivalent: phasing_MIR_der/reflns_criteria Criteria used to limit the reflections used in the phasing calculations. XmlmmCIF equivalent: phasing_MIR_der/id The value of _phasing_MIR_der.id must uniquely identify a record in the PHASING_MIR_DER list. Note that this item need not be a number; it can be any unique identifier.