Anharmonic Damping of Phonon Modes in the Face-Centered Cubic Metals

For the fcc metals Cu, Ag, Au, and Al, a theoretical analysis has been made of the one-phonon linewidth due to cubic anharmonic interactions. Third-order central and angular force constants have been obtained by using the symmetry properties of the lattice to relate the force constants with the experimental third-order elastic moduli. The convergence of the value of the nearest-neighbor third-order force constant has been studied as a function of the range of the cubic interactions. We have found that for metals for which the third-order Cauchy relations are violated it is necessary to introduce cubic angular forces to obtain a convergent value of the nearest-neighbor force constant. For Al and Cu the evaluated linewidths are compared with experimental data.