Comment on "High-temperature superconductivity in transition metallic hydrides MH (M = Mo, W, Nb, and Ta) under high pressure" by M. Du, Z. Zhang, H. Song, H. Yu, T. Cui, V. Z. Kresinc and D. Duan, , 2021, , 6717.

The Monkhorst-Pack scheme is applied in , 2021, , 6717 to study superconductivity in transition metallic hydrides, implying that umklapp phonons have been excluded. But in a superconductor scattered electrons should be able to cover the entire Fermi surface so that umklapp phonons must be included. The authors should take care to explain if and how measures were taken to include umklapp phonons for electron-phonon scattering.