Ab initio MO studies of DCNQI molecules

We study electronic states of the one-dimensional (DCNQI)(2)M (M=Li and Ag) salts based on the full configuration interaction (CI) method using effect ive Hamiltonians from ab initio molecular orbital (MO) theory. In the tetra mer and octamer models, the ground state has the antiferromagetic (AF) and charge ordering correlations which correspond to the 2 k(F) spin density wa ve (SDW) and 4 k(F) charge density wave states (CDW). In the octamer model. it is found that some low-lying excited states have similar spill-flipped CDW correlations and the AF correlation is weakened. Keywords: Ab initio qu antum chemical methods and calculations, Organic conductors based on radica l cation and/or anion. salts, Metal-insullator phase transitions.