Effective ionic Hamiltonians from many-body second-quantization Dyson orbitals: The Kondo resonance in triangulenes...

We present a theoretical study of the Kondo resonance in the family of n-triangulenes adsorbed on Au(111). The electronic structure and equilibrium geometry for both C 13 H 9 (2T) and C 22 H 12 (3T) are obtained from ab initio Hartree-Fock and density functional theory calculations. Generalization to other members of the family can be achieved along similar lines. The Hartree-Fock molecular wavefunctions provide the starting point for a multi-orbital many-body description based on a second-quantization formulation of Feynman-Dyson orbitals. This approach leads to an effective ionic Hamiltonian that describes charge fluctuations between the molecule and the metallic substrate for the spin 1 2 and 1 states of 2T and 3T, respectively. The Kondo resonance is then computed within a fourth-order expansion in the interaction using an equation of motion Green's functions formalism. This basic ab initio theoretical approach explains various microscopic mechanisms originating in many-body features related to even and odd members of the n-triangules family, establishing a direct connection with recent low-temperature high-resolution scanning tunneling spectroscopy experiments.