Crystal Data Card Descriptions

The card descriptions which follow indicate the data required on each type of Crystal Data card, and define how it should be presented.

Initial Letters

Most initial letters have been assigned. Y and Z introduce comment cards. I is for general instructions, and X has been deliberately left for the user. The remaining assigned letters are used for cards containing specific items of crystallographic data.

Systems of Axes

Three systems of axes are used in different places in CCSL. They are:

1.

the direct space crystallographic axes with $x,y,z$ parallel to the cell edges a, b, c . They are used for atomic positions, zone axes etc.

2.

The reciprocal space axes with $x,y,z$ parallel to the reciprocal cell edges a$^*$, b$^*$, c$^*$. They are used for reflection indices etc.

3.

A standard set of orthogonal axes with:

$x$ parallel to a$^*$ (100)
$z$ parallel to c [001]
$y$ making up a right-handed set

These axes are used to describe the crystal form and for spin directions. They will be referred to as CCSL orthogonal axes.