IMIT researcher participates as guest speaker at international congress in China

Dr. Agustín Aucar, a researcher at IMIT, gave an invited talk at the 11th Triennial Congress of the International Society for Theoretical Physical Chemistry (ISTCP 2024) in Qingdao, China.

His presentations focused on a novel relativistic theory that allows establishing a formal relationship between two molecular properties, nuclear magnetic screening and nuclear spin-rotation coupling, properties of special interest for the study of molecules containing at least one heavy element (elements below the fourth row of the Periodic Table). This theory, developed by Dr. Aucar together with other members of IMIT and then applied also together with Dutch collaborators, is based on Dirac's quantum mechanics and generalizes an analogous non-relativistic theory, proposed in the 1950s and 1960s by the Americans Ramsey and Flygare.

The most recent advances in Dr. Aucar's research have made it possible to demonstrate that the relationship that these Argentine researchers had proposed a few years ago is valid not only when considering electrodynamic interactions (the most important ones in atoms and molecules), but is also applicable when considering effects that violate a fundamental symmetry of nature (parity). These latter effects, which come from electroweak interactions involving sub-nuclear particles and electrons, allow us to delve deeper into the study of the Standard Model of Particle Physics in molecular systems.

Key points of the research:

• Overcoming the limitations of non-relativistic models: The Ramsey-Flygare theory, although elegant and accurate, is not applicable to molecules containing heavy elements, where relativistic effects are very significant.
• Relativistic approach: The new theory, based on Dirac's quantum mechanics formalism, incorporates relativistic effects, and allows to elucidate (among others) the central role played by spin-orbit couplings in providing a precise relationship between molecular properties.
• QED formalism and inclusion of electroweak interactions: The proposed theory is not only valid in the context of quantum electrodynamics (QED), but also allows to accurately link the contributions to these two properties that violate parity symmetry (and that come from electroweak interactions).
• Computational tool: New implementations have been made in a reference computational code in the area, to model and find applications to this new relationship between molecular properties.