  G4CMP simulates phonon and charge transport in cryogenic semiconductor
crystals using the Geant4 toolkit. The transport code is capable of simulating
the propagation of acoustic phonons as well as electron and hole charge
carriers. Processes for anisotropic phonon propagation, oblique charge-carrier
propagation, and phonon emission by accelerated charge carriers are included.
The simulation reproduces theoretical predictions and experimental observations
such as phonon caustics, heat-pulse propagation times, and mean charge-carrier
drift velocities. In addition to presenting the physics and features supported
by G4CMP, this report outlines example applications from the dark matter and
quantum information science communities. These communities are applying G4CMP
to model and design devices for which the energy transported by phonons and
charge carriers is germane to the performance of superconducting instruments
and circuits placed on silicon and germanium substrates. The G4CMP package is
available to download from GitHub: github.com/kelseymh/G4CMP.
