Tecnai on-line help manual -- Options - UT Southwestern

<strong>Tecnai</strong> on-line help Options 107Options Software version 27.10 k-Space Control CrystalThe k-Space Control Crystal Control Panel contains severalfunctions for using k-Space Control.NewIn order to start working on a new crystal or phase, the software must know the crystal structure. To thispurpose the lattice parameters and crystal-structure type must be entered in the Crystal data dialog. Theprogram works on a triclinic basis so for crystals with higher symmetry, the symmetry derives simplyfrom the lattice parameters (all angles 90° and dimensions the same for cubic, all angles 90° and a=b fortetragonal, etc.). For hexagonal crystals the rhombohedral notation must be used.The Crystal datadialog.For simplified entering of the data, a set of crystal structures has been predefined (cubic, tetragonal,etc.). These are used simply to avoid defining unnecessary entries (e.g. when cubic is selected allangles will be set to 90° and b and c will be equal to a). These crystal structures are not imposed on theunderlying calculations (as stated above, all is done on a generalized, triclinic basis). Thus a selection ofcubic with a value of 0.52 for a is equivalent to selecting triclinic and entering the 0.52 for a,b and c andsetting all angles to 90° (but selecting the cubic crystal structure is less work than entering all the valuesby hand).