# Transforming Crystal Field Parameters by Rotation of the Coordinate System

There is a special program cf2mcphas for rotating crystal field parameters (Stevens Notation) given in the orientation xyz to the McPhase notation yzx. The original crystal field parameters have to be given in a file of the above format of a single ion parameter file. Output is written to stdout. Note, there is also a program mcphas2cf for transforming parameters back. For more general rotations of crystal field parameters you can use the program rotateBlm(see chapter 18).

As an example we consider a tetragonal system, where the crystal field parameters are usually given such that xyz - we denote these parameters as . For tetragonal symmetry only and are not zero. In order to use these parameters in mocule cfield, they have to be transformed to a coordinate system with . Denoting the new crystal field parameters which are to be used as the transformation is given by

As a second example we consider an orthorhombic system, where the crystal field parameters are given such that xyz - we denote these parameters as . For orthorhombic symmetry only and are not zero. In order to use these parameters in mocule cfield, they have to be transformed to a coordinate system with . Denoting the new crystal field parameters which are to be used as the transformation is given by

As a second example we consider an dhcp system with quasi cubic sites, where the crystal field parameters are given such that xyz - we denote these parameters as . Only and are not zero. In order to use these parameters in mocule cfield, they have to be transformed to a coordinate system with . Denoting the new crystal field parameters which are to be used as the transformation is given by

The general transformation matrices are given by

Subsections
Martin Rotter 2017-01-10