Influence of $s$-$d$-hybridization of the electrical conductivity of liquid transition metals

Betarded Green's functions are used to develop a theory of the electrical conductivity of liquid transition metals with systematic allowance for the hybridization of the $s$- and $d$-states of the conduction electrons. It is shown that the conductivity can be represented as a sum of three terms, one of which is due to the scattering of $s$-electrons by ions, including resonance scattering by $d$-states, the second is due to tunneling of $d$-electrons through $d$-states, and the third is due to transitions of almost localized $d$-electrons to delocalized $s$-states and reverse transitions from $s$- to $d$-states. Expressions for each of the contributions are obtained in the framework of perturbation theory with respect to the pseudopotential of the electron-ion interaction, the hybridization potential, and the resonance integral.