Strong-coupling electron-phonon superconductivity in noncentrosymmetric quasi-one-dimensional K2Cr3As3

I study the lattice dynamics and electron-phonon coupling in noncentrosymmetric quasi-one-dimensional K2Cr3As3 using density functional theory based first principles calculations. The phonon dispersions show stable phonons without any soft-mode behavior. They also exhibit features that point to a strong interaction of K atoms with the lattice. I find that the calculated Eliashberg spectral function shows a large enhancement around 50 cm-1. The phonon modes that show large coupling involve in-plane motions of all three species of atoms. The q dependent electron-phonon coupling decreases strongly away from the qz=0 plane. The total electron-phonon coupling is large, with a value of λep=3.0, which readily explains the experimentally observed large mass enhancement.