Binding energy of holes in the two d-π chains

I propose new two chains composed of d electrons with localized spin 1/2 and itinerant pi electrons to research the possibility of superconductivity with spin gaps in organic compounds. I have investigated the effects of the antiferromagnetic exchange interaction between d- and pi-electron spins, JK, that between pi-electron spins along the rung, J(v), and the transfer energy of ir electron along the rung, t(v), on the bound states of holes. I have computed the binding energy Eg Of two holes doped away from half-filling using a mean-field approximation and periodic boundary conditions. As J(K) and J(v) increase, Eg's decrease and are negative for larger values than the critical valves J(Kc) and J(vc), while E-B < 0 for smaller values of t(v) than t(vc). As a result, the holes on rungs form a bound state and the bound states are stabilized for J(K) greater than or equal to J(Kc), J(v) greater than or equal to J(vc) and t(v) less than or equal to t(vc). The spin Of two holes is singlet.