Besides creating entirely new material definitions for G4CMP, there may be occasions when you want to run jobs with modified values of some of the individual parameters. For example, scanning one or more parameters to align with your experimental data, or to assign a systematic uncertainty in an analysis. We do not have a mechanism for doing this for individual parameters via macro commands; this page describes how do so via local CrystalMaps replacement directories, and provides some suggestions for managing a "parameter scan" in a hopefully coherent way.
The location of the material definitions is specified by the $G4LATTICEDATA environment variable, which is assigned by the g4cmp_env.sh (.csh) setup script. That envvar points to the G4CMP/CrystalMaps directory, which contains a subdirectory for each material (Ge/, Si/, Al2O3/, etc.); those subdirectories in turn contain a config.txt file with all of the phonon and charge-carrier parameters for that material.
If you want to change the value of any parameter in config.txt, you need to copy the whole file and edit it (the G4LatticeManager and Reader code do not support stacking partial files together). That file should then be put into a local directory tree like myPersonalMaterials/Ge/config.txt (or whatever material you're working with). Given that, you can then use the macro command
/g4cmp/LatticeData myPersonalMaterials
to point to your custom version.
If you are running a series of simulations across a range of parameter values, you will need separate directories for each one. We strongly discourage running multiple different jobs by editing a single file. Not only can you not do that at all if you submit multiple jobs in parallel, it also reduces your ability to associate a given job with a given configuration. We recommend instead creating a separate top-level directory for each parameter value, with names like "<param>_<value>" That allows your job macros to self-document the parameter value they used.