Predicting the conductance of strongly correlated molecules: the Kondo effect in perchlorotriphenylmethyl/Au junctions

Stable organic radicals integrated into molecular junctions represent a practical realization of the single-orbital Anderson impurity model. Motivated by recent experiments for perchlorotriphenylmethyl (PTM) molecules contacted to gold electrodes, we develop a method that combines density functional theory (DFT), quantum transport theory, numerical renormalization group (NRG) calculations and renormalized super-perturbation theory (rSPT) to compute both equilibrium and non-equilibrium properties of strongly correlated nanoscale systems at low temperatures effectively from first principles. We determine the possible atomic structures of the interfaces between the molecule and the electrodes, which allow us to estimate the Kondo temperature and the characteristic transport properties, which compare well with experiments. By using the non-equilibrium rSPT results we assess the range of validity of equilibrium DFT + NRG-based transmission calculations for the evaluation of the finite voltage conductance. The results demonstrate that our method can provide qualitative insights into the properties of molecular junctions when the molecule-metal contacts are amorphous or generally ill-defined, and that it can further give a fully quantitative description when the experimental contact structures are well characterized.A. D. and I. R. acknowledge the financial support from the EU project ACMOL (FET Young Explorers, No. 618082). A. D. received additional support from EU Marie Sklodowska-Curie project SPINMAN (No. SEP-210189940) and from the Ministerio de Economía y Competitividad de España (No. FPDI-2013-16641). I. R. acknowledges additional financial support from the EU H2020 programme PETMEM project (Grant No. 688282). I. R. thanks the Cambridge CSD3 HPC centre for providing part of the computing resources. W. H. A., L. C. and D. V. acknowledge the financial support from the Deutsche Forschungsgemeinschaft through TRR80/F6, TRR80/G7 and the FOR1346/P3. E. Muñoz acknowledges financial support by Fondecyt (Chile) No. 1141146. M. M. Radonjić acknowledges the support from Ministry of Education, Science, and Technological Development of the Republic of Serbia under project ON171017. S. Kirchner acknowledges support by the National Key R&D Program of the MOST of China, grant No. 2016YFA0300202, the National Science Foundation of China, grant No. 11774307 and No. 11474250, and the U.S. Army RDECOM – Atlantic Grant No. W911NF-17-1-0108.Peer reviewe