Translation-invariant bipolarons and the problem of high-temperature superconductivity

It is shown that the bipolaron ground state is described by a delocalized wave function. For a two-parameter wave function, the lowest variation estimate of the ground state energy in the strong coupling limit is found to be $E=- 0,414125 \alpha ^2$. This is much lower than that derived with the use of the localized bipolaron wave function. The results obtained testify to the possibility of a bipolaron mechanism of high-temperature superconductivity.