Volume 2 Chapter 7 Numeric Sub-menu *MDATE

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*METRICCLASS

Function

*METRICCLASS is used to test for a specified value or range of values of the metric class number.

Remarks

Mighell and Rodgers have published (Acta Crystallogr.,Sect.A 36,321,1980) a full description of the metric classification of unit cells.

This classification involves 44 reduced forms which can be derived from reduced cells.

Each reduced form has associated with it a transformation matrix that will convert the reduced cell to the conventional cell.

Graphics QUEST3D Procedure

Select *METRICCLASS from the NUMERIC sub-menu and respond to the standard numeric prompts.

Basic QUEST Procedure

Ex.

T1 *METR .EQ. 16

This will register a hit for all entries having metric class 16.

The characteristics of reduced form number 16 are:

Reduced form matrix   1st row   a.a   b.b   b.b   (b=c)
                      2nd row   0     0     0
Reduced form type      -
Bravais lattice       primitive trigonal
Cell transformation (reduced to conventional) 010/001/110

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Volume 2 Chapter 7 Numeric Sub-menu *MSDBIB.