Recent data on the single-domain resistivity of YBa2Cu3O7 are analyzed using the local-density-approximation calculations of the plasma frequencies and Fermi velocities. It is shown that the transport coupling constants lambda tr for all three directions come out to be of the same order, namely about 1.5. The corresponding mean free path l=11 AA at T=300 K, which dispels the popular notion that the local-density-approximation band structure yields unreasonably large lambda and small l values. The possibility of an anisotropy in lambda tr and of a difference between lambda and lambda tr is discussed with the help of results from rigid-muffin-tin calculations of the Hopfield factors eta .
 

Physical Review B, 45 2509-11, 1992.