Ruprecht-Karls-Universität Heidelberg

Physics of Isotopologues

Halua Pinto de Magalhaes - Alexander von Humboldt fellow

Research


Many fields of Earth sciences benefit from the knowledge of mineral formation temperatures. For example, carbonates are extensively used for reconstruction of the Earth’s past climatic variations by determining ocean, lake, and soil paleotemperatures. The fundamental physical processes during the formation of such carbonate minerals are, in principle, accessible with theoretical models by, e.g., providing the isotopic ratios of natural tracers such as C-13 and O-18. More specifically, molecular modeling and simulation, which is nowadays an essential enabling technology in almost all areas of contemporary science and engineering, is the key to our interdisciplinary research. Yet, the main challenge of interpreting such complex chemical systems by comparing ab-initio calculations with measurement results is in providing a suitable theoretical framework for our specific experimental set-up. We therefore are in the process to gain a profound molecular understanding of carbonate minerals in contact with liquids on the basis of electronic structure theory. In the end, we will use our detailed knowledge of the interface structure and its dynamic properties which allows to elucidate the physico-chemical processes, to predict (kinetic) isotope effects and to compare with experimental measurements.

We are using state-of-the-art computational methods to obtain a detailed understanding of the chemical systems under study on a molecular level. Our overall aim is to gain fundamental insights into the physico-chemical processes responsible for the fractionation of natural isotope tracers during analysis processing as well as the formation of carbonate minerals under environmental conditions. Herein, the metadynamics technique offers an efficient AIMD approach to accelerate rare events towards specific reaction coordinates. That allows rigorously assessing the influence of entropic effects along the reaction pathway which is required to estimate rate constants. Critical for the magnitude of these rate constants are the inclusion of approximate nuclear quantum effects (NQE), especially zero-point energy and tunneling. This NQEs are incorporated in more sophisticated methods such as the path integral (PI) approaches, which are able to determine isotopic fractionation factors with experimental accuracy. The reason for the superiority of the PI methods is in accounting for several deficiencies encountered in theoretical kinetics, such as the influence of anharmonicity, multi-dimensional tunneling, and recrossing at a dividing surface. This part of the project will be performed in collaboration with Dr. Mariana Rossi (Fritz-Haber-Institute Berlin, Germany).

Professional Experience


2017−2018 Postdoctoral research fellow, University of Zürich (UZH), Zürich, Switzerland, Supervisors: Prof. Dr. Jürg Hutter & Dr. Marcella Iannuzzi.
Nanofluidic Transport through two-dimensional nanoporous materials.

2016 Postdoctoral research fellow, Swiss Federal Institute of Aquatic Science (Eawag), Dübendorf, Switzerland, Supervisor: Prof. Dr. Rolf Kipfer.
Exploring molecular-resolved mechanisms of isotopic fractionation of noble gases upon diffusion in water by the use of AIMD simulation techniques.

2011−2015 PhD in Chemistry, Swiss Federal Institute of Technology (ETHZ), Zurich, Switzerland, Supervisors: PD Dr. H. P. Lüthi and Prof. Dr. A. Togni.
PhD Thesis: Exploring the Chemistry of λ3-Iodanes: The Role of Hypervalent Bonding.

2015 Civil service mission in Cape Verde, Eawag, Dübendorf, Switzerland, Supervisors: Dr. Annette Johnson & Numa Pfenninger.
Installation and implementation of community water filters for the removal of excess fluoride in Monte Trigo (Ilha de Santo Antão).

2014 Short term scientific visit in Belgium, Ghent University (UGent), Gent, Belgium, Supervisor: Prof. Dr. Patrick Bultinck.
Acquire knowledge and skill of the methodology of domain average Fermi holes to cast complex electronic structure relations into conceptual models.

Publications


H. Pinto de Magalhães, O. Sala, H. P. Lüthi, PATAI’S Chemistry of Functional Groups: The Chemistry of Hypervalent Halogen Compounds, 2019, John Wiley & Sons Ltd: “Fundamental Aspects of Structure, Bonding and the Reactivity of Hypervalent Iodine Compounds.”

H. Pinto de Magalhães, A. Togni, H. P. Lüthi, J. Org. Chem., 2017, 82 , 11799−11805: “The Importance of Non-Classical σ-Hole Interactions for the Reactivity of λ3 -Iodane Complexes”.

H. Pinto de Magalhães, M.S. Brennwald, R. Kipfer, Environ. Sci.: Processes & Impacts, 2017, 19, 405−413: “Diverging effects of isotopic fractionation upon molecular diffusion of noble gases in water: mechanistic insights through ab initio molecular dynamics simulations”.

H. Pinto de Magalhães, H. P. Lüthi, P. Bultinck, Phys.Chem.Chem.Phys., 2016, 18, 846−856: “Exploring the Role of the 3-Center-4-Electron Bond in Hypervalent λ3-Iodanes Using the Methodology of Domain Averaged Fermi Holes”.

H. Pinto de Magalhães, H. P. Lüthi, A. Togni, J. Org. Chem. 2014, 79, 8374−8382: “Breaking Down the Reactivity of 3 -Iodanes: The Impact of Structure and Bonding on Competing Reaction Mechanisms”.

H. Pinto de Magalhães, H. P. Lüthi, A. Togni, Org. Lett. 2012, 14, 3830−3833: “Reductive Eliminations from λ3 -Iodanes: Understanding Selectivity and the Crucial Role of the Hypervalent Bond”.

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