Abstract:
A new functional representation for strongly correlated systems is used to study the evolution of the electron spectrum in the Hubbard model with increasing $U$. It is established that the parametric instability of the ground state of a strongly correlated metal with 1/4 filled band
can be described by linear transformations of the dynamic fields. It is shown that the operator of the transformations has a nontrivial kernel. It is noted that the considered system can serve as a point of departure for interpreting structural transitions of $2k_F$ and $4k_F$ types
in the quasione-dimensional metal MEM(TCNQ)$_2$.
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