First-principles analysis of the charge transfer in the NMP-TCNQ molecular metal and (NMP)x(Phen)1-xTCNQ solid solutions

A first-principles DFT study of the electronic structure of the two-chain molecular conductor NMP-TCNQ is reported. It is shown that the charge transfer occurring in this salt is not 1 but 2/3, finally settling the debate concerning the real charge transfer in this molecular metal. These calculations also lead to a simple rationalization of the three different regimes of 2kF and 4kF CDW instabilities occurring in the solid solutions (NMP)x(Phen)1−xTCNQ