Speaker: Prof Amir O. Caldeira
Affiliation: Universidade Estadual de Campinas, Instituto de Física Gleb Wataghin
Host: Asst Prof Vitor Pereira
Location: Click HERE for directions
Abstract Details: We study the magnetic properties of electrons in small discrete rings with 3 ≤ N ≤ 6 sites and Ne = N electrons, some of which can be regarded as a simplified version of real aromatic molecules. In particular, the ring with six sites and six electrons is our prototype of the benzene molecule. Aiming at that goal we employ the Hubbard model with appropriate parameters t and U, and confirm it cannot account for the anisotropy of the diamagnetic susceptibility of some aromatic molecules. Benzene is a standard example of that. Therefore, we propose an extension of the Hubbard model with an extra interelectronic momentum-momentum coupling which is an effective two-body interaction between the itinerant electrons mediated by virtual transitions of the binding electrons of our pseudo molecules. Our results show that this extension of the Hubbard model is able to cause an enhancement of the anisotropic diamagnetic susceptibility in some specific cases.
About the Speaker: A. O. Caldeira
Graduated in physics from Pontifícia Universidade Católica do Rio de Janeiro (1973), MSc in physics from Pontifícia Universidade Católica do Rio de Janeiro (1976) and PhD in physics from University of Sussex (1980). Has experience in theoretical physics, focusing on condensed matter physics, and acting mainly on the following subjects: quantum dissipation, macroscopic quantum effects and low dimensional electronic systems.