Using Dicvol06
Use as input data all available diffraction lines (N_TOTAL). Only the first N (eg 20) lines will be used for the search of solutions. These solutions are subsequently used automatically for reviewing all N_TOTAL input data. The impurity tolerance N_IMP is related only to the N lines used for searching solution(s) (of course, other unindexed lines can be found among the extra input lines in the reviewing process).
Be careful in using the impurity tolerance: spurious lines increases the risk to miss the correct solution!
If a solution is found in a volume shell, the search is exhaustive within this shell. thus, the search is not extended to the next volume shell (for the symmetry being analysed). if needed, the user can run again Dicvol06, for selected lattice systems, taking the higher volume value of the already analysed volume shell as VOLMIN in the new input parameters set.
Generally, runs with OPTION =1 take longer CPU times and the number of mathematical solutions is greater (it has been limited to the first 100 found solutions in the Dicvol06 output file). By acting on the input FOM (greater FOM in Line 5) solutions with lowest FOMs can be rejected).
Be careful: as soon as 100 solutions are found the calculation stops.
Dicvol06 offers the possibility to analyse your input data for the presence of a zero-point error. The method employed can suggest more than one or two solutions (due to uncertainty in searching harmonic diffraction lines). This option is to be used prior the indexing process. Please, as far as possible avoid the use of this facility by ensuring the quality of your collected data!
Usual 'zero-point' errors (if not too big) are generally corrected by the least-squares refinement of the 'zero-point' parameter ZERO_REF, together with the refinement of cell parameters. ZERO_REF is, in fact, an extra degree of freedom in the refinement. it includes all systematic measurement errors from different origin, e.g. zero-point shift, sample-surface displacement, umbrella effect, transparency, capillary displacement, ...
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