Low-temperature electrical resistivity of noble metals

We have accomplished a study of the low-temperature electrical resistivity for the noble metals silver and copper. We have described the Fermi surface of the noble metals by the simple eight-cone model and have taken into account two-orthogonalized-plane-wave corrections which are very important at the lowest temperatures. The use of the standard trial function in the variational formula for the resistivity makes the calculation more applicable to the temperature-dependent resistivity of impure samples. This interpretation is supported by comparison with the available experimental data. Our results evidence the preponderance of the "umklapp" contribution to the low-temperature resistivity over the normal one. Moreover, they show that the resistivity as a function of temperature does not follow a well-defined power law, but, if one assumes the validity of a simple relation $\rho \sim T^n$, the exponent $n$ varies continuously ranging from a value of nearly 6 to a value of nearly 4 in the region $T=1-15\mathrm{}$ K.