The candidate list

The so-called "candidate list" on the lower left-hand side of the Match! window displays a list of all entries in the current answer set. These entries can either result from a search-match operation ("candidate entries") and/or from a set of selection criteria (database retrieval).

The following columns/data are displayed for each entry:

Color

In this column the color of the corresponding pattern in the diffraction pattern graphics is given. The color of the unknown sample's pattern is blue by default, while the colors of the database patterns (starting in the second row) are assigned automatically, depending on the order of marking/selecting. For instance, the diffraction pattern of the entry which has been marked or selected first is automatically displayed in red, the second marked entry in green etc. You can also assign colors manually using the Colors and line styles dialog that can e.g. be opened from the "Tools" menu, or by pressing the corresponding button in the main toolbar at the top.

Qual.

This is the quality mark of the diffraction pattern as given by the ICDD editors (or by you, in case of user database entries). Possible values are * (excellent), C (calculated), R (Rietveld), I (indexed), B (none), O (doubtful) and D (deleted).

Entry

Entry number according to the new ICDD PDF numbering scheme. Entry numbers < 95-000-0000 refer to PDF database entries; larger entry numbers belong to other reference databases (e.g. user database).

Formula

Formula sum

Candidate phase

This is the so-called "PDF index name", i.e. the name of the compound/phase as given by the ICDD editors, or "chemical name" in context with the user database. If a mineral name is present, it is given in brackets behind the name.

P(2theta)

Probability that the entry's pattern matches the one of the unknown sample with regard to the peak positions. The possible range of this value is 0.0 (no matching) to 1.0 (full matching).

P(I/I0)

Probability that the entry's pattern matches the one of the unknown sample with regard to the intensities of the correlated peaks. The possible range of this value is 0.0 (no matching) to 1.0 (full matching).

I scale fct.

The intensities of the entry's peaks have been multiplied by this factor in order to obtain the best possible agreement P(I/I0) with the unknown pattern.

I/Ic

This column only contains values for entries which include the I/Ic factors. Based on these values along with the intensity scaling factor given in the previous column, Match! is able to perform a semi-quantitative analysis using the "Reference Intensity Ratio method" (de Wolff, Visser (1964)). If only one of the selected entries does not contain an I/Ic factor (or if no corresponding default value is given on the "General" page of the "Options" dialog), the values for the remaining selected entries will not be displayed as well.

FoM

This is the so-called "figure-of-merit", i.e. a number which is calculated from the various measures of agreement between database and unknown pattern (e.g. P(2theta), P(I/I0) etc.).
If the "color differentiation according to FoM" option is activated, the FoM value is also displayed "graphically" as the background color of the FoM column. If the FoM of the corresponding entry is close to 1.0, the bar will be deep green. On the other hand, if the FoM is close to its minimum value, the color will be red. Any value in between will be interpolated, so that the colors of the bars can reach from green over yellow and orange to red. If the FoM is below the minimum value, the background color will be blue. The background color of the FoM value will also be the background color for the data sheet of the corresponding entry.

Sorting: You can sort the candidate list with regard to any of the columns in ascending or descending order. This sort criterion can be changed simply by clicking on the corresponding column headers. The current sort order is indicated by the triangle to the right of the column header texts.

Printing: You can print the candidate list by selecting the "Print..." command from the "File" menu. Afterwards, select "Candidate list" in the "Print" dialog which opens, then press "OK".

Exporting: It is possible to export the candidate list to an ASCII tabular file containing ';' characters as separators (a so-called "csv-file"), as a HTML- or pdf-file, or as a Match! answer set file (*.mta). In order to do so, please select the "Candidate list" command from the "Export" submenu of the "File" menu.

Updates: As soon as some parameter used in the figure-of-merit calculation (e.g. the restrict to range of unknown pattern" option) has been changed by the user, the FoM values of all entries in the candidate list are recalculated immediately. Hence, the user has an instant feedback on his/her operations. However, it is important to understand that the changes only affect the current candidate list entries ! In some cases it is strongly recommended to perform a whole new search-match operation after parameter changes !

See also: