See our documentation at
https://docs.quantumatk.com/manual/Types/Mobility/Mobility.html.
"The implementation in QuantumATK of the isotropic scattering rate method essentially follows BoltzTrap, Ref. [MS06]. Major differences to the description in Ref. [MS06] are:
QuantumATK allows for an energy dependent inverse relaxation time.
The band velocities in QuantumATK are calculated using first order perturbation theory and are thus exact and without any problems at band crossings. The energy integrations are performed using the tetrahedron method [BJA94].
[BJA94] P. E. Blöchl, O. Jepsen, and O. K. Andersen. Improved tetrahedron method for brillouin-zone integrations. Phys. Rev. B, 49:16223–16233, Jun 1994. doi:10.1103/PhysRevB.49.16223.
[MS06] (1, 2) Georg K.H. Madsen and David J. Singh. Boltztrap. a code for calculating band-structure dependent quantities. Computer Physics Communications, 175(1):67 – 71, 2006. doi:http://dx.doi.org/10.1016/j.cpc.2006.03.007."
For the physical meaning of isotropic/constant relaxation time, you may consult some textbook on Solid State Physics, e.g., by Aschcroft & Mermin.
