Not always you can obtain the correct structure solution in default. In a typical Direct Methods Procedure more sets of phases (trials) are generated and ranked according to a figure of merit (see next Sections) and only the best trial is used to calculate a Fourier map. Because of the unavoidable errors on the phases, the figure of merit can fail to evaluate the best trial, so is strictly suggested to develop the other trials by menu 'Solve' > 'Explore other trials'
and window like these will be opened.
You can read the CFOM, a figure of merit estimating the quality of the trial. If the trial has been already developed (done='yes'), you can read the RF figure of merit that quantifies the agreement between the structure factors extracted and calculated by the model.
Check the button in first column to decide which trial will be developed and press the button . If you check the button 'Select new trial', all the trial not already explored will be automatically selected and developed. You can choose three different action:
1)RBM: Resolution Bias Modification is the default action.
2)Fourier: classical Fourier refinement.
3)E-map: the first electron density map calculated directly after the phasing process by DM.
At the end all the trials appear ordered according to the RF and you can click on a row of list to visualize the corresponding structure model.
The command %alltrials can be used to automatically explore all trials. An example for the structure merca:
%Structure merca
%Initialize
%Job merca
%Data
Cell 7.885 5.976 14.949 90.0 100.48 90
SpaceGroup p 21/c
Content c 28 O 8 S 4 h 24
Pattern pd_0002.pow
Wavelength 1.54056
filetype xy
%extra
%normal
%invar
%phase
%alltrials
%continue
Created with the Personal Edition of HelpNDoc: Easily create HTML Help documents