Kondo Temperature for the Two-Channel Kondo Models of Tunneling Centers

A two-channel Kondo (2CK) non-Fermi liquid state in a metal resulting from the interaction between electrons and structural defects modeled by double-well potentials (DWP) is revisited. Account only of the two lowest states in DWP is known to lead to rather low Kondo temperature, $T_K$. We prove that the contribution of higher excited states reduces $T_K$, if all of the intermediate states are taken into account. Prefactor in $T_K$ is shown to be determined by the spacing between the second and the third levels ${\epsilon }_3$ in DWP rather than by the electron Fermi energy ${\epsilon }_F$. Since ${\epsilon }_3\ll {\epsilon }_F$ there is no microscopic model of movable defects which may justify 2CK phenomenology.