Electronic structure calculations on extended metal atom chains. Insights on structural, magnetic and transport properties

Identifier:  TDX:2467

Handle: https://hdl.handle.net/20.500.11797/TDX2467

Authors:  Spivak, Mariano Alejo

Abstract:
In this work we use different computational methods in the study of the properties of Extended Metal Atom Chains. The structural flexibility of trichromium chains has been simulated with CASSCF/CASPT2 and symmetric and asymmetric structures were identified in an extremely flat energy landscape. Based on these results, Ab initio molecular dynamic simulations were performed to understand how the thermal energy modifies the proportion of cited structures. In addition, the metal-metal bonding of chromium compounds was characterized using the Effective Bond Order (EBO) model with the natural occupation numbers of the CASSCF wave function. Furthermore, magnetic coupling constants were computed for nickel bimetallic and EMACs compounds, using two different approaches. Minimal active space MC-PT2 was performed with improved molecular orbitals based on state-average calculations, and a recently developed method (MCPDFT) used for the magnetism of large EMACs, showing good results in the five-nickel compound. Finally, the electron transport properties were simulated for two ruthenium EMACs. We propose the use of a metallic gate electrode to modulate the molecular levels of the compounds and achieve redox active species. In addition, another more chemically intuitive approach was tested, that consist of forming an ionic pair in-situ.