First-principle Calculations of Electron-Phonon Interactions in $A^{II}{B}^{IV}{C}_2^V$ Crystals

$Ab-initio$ probabilities of phonon-assisted intervalley scattering of electrons in the conduction bands of ternary chalcopyrite compounds $ZnSi{P}_2$ and $ZnGe{P}_2$ between the central $\mathrm{\Gamma }$ minima and the lowest lateral minima (valleys) at $T$ and $N$ points have been calculated using the density functional theory. The equilibrium parameters of crystal structures, spectra of electrons and phonons are calculated self-consistently and are in fairly good agreement with the experiment and available theoretical calculations. The electron-phonon coupling constants with short-wave (inter-valley) phonons in the chalcopyrite phosphides are close to their values in $Si$, $Ge$ and in binary analog $GaP$.