Les Mardis de la chimie | Julia Contreras-Garcia (LCT) "Constructing new model to predict superconductivity"

A room temperature superconductor is probably the most desired system in solid state physics. So far, the greatest advances, cuprates, pnictides and number of others were obtained in a serendipitous way. As there is no clear theory for these superconductors, it is difficult to predict where progress will be made. In contrast the Bardeen-Cooper-Schrieffer (BCS) theory gives a clear guide for achieving high Tc, and hydrogen seems to be a main clue. Within this approach, the recently reported superconductivity at 190 K in compressed H2S [1] has been arguably the biggest discovery in the field since the superconducting cuprates nearly 30 years ago.
However, a microscopic understanding of why this particular material features such a strong coupling is still missing. We have recently shown that the underlying chemical structure and bonding need to be characterized for a good comprehension of the chemical composition-superconductivity relation.
We have constructed simple metal and BCS models showing that the Electron Localization Function [2] can be used to define a quantity called the networking value, which should provide insight into the superconducting activity.
By analyzing through DFT calculations the structural and electronic properties of nearly 200 compounds predicted to be superconductors in the literature, we have shown that the networking value correlates well with the predicted critical temperature, much better than any other descriptor analyzed thus far. And this, for all bonding types [3].
The discovery of the positive correlation between superconductivity and the bonding network offers the possibility of screening easily hydrogen-based compounds and, at the same time, sets clear paths for chemically engineering better superconductors.

References
[1] A. P. Drozdov, M. I. Eremets, I. A. Troyan, V. Ksenofontov, and S. I. Shylin.
Conventional superconductivity at 203 kelvin at high pressures in the sulfur hydride system.
Nature 2015, 525, 73
[2] A. D. Becke and K. E. Edgecombe.
A simple measure of electron localization in atomic and molecular systems.
The Journal of Chemical Physics 1990, 92, 5397
[3] F. Belli, T. Novoa, J. Contreras-Garcia and I. Errea,
Strong correlation between electronic bonding network and critical temperature in hydrogen-based superconductors.
Natur. Comm. 2021, 12, 5381

Biographie - I did my PhD in Universidad de Oviedo (Spain) under the advisory of Prof. J. M. Recio.  My thesis holds two prices: Best Thesis 2008, University of Oviedo and Best Thesis by the Chemistry Association in Asturias 2008. I then moved as a postdoctoral fellow at Duke University under the advisory of W. Yang and D. Beratan, with a Fulbright grant. During this time we introduced a new index, NCI (Non Covalent Interactions) which enables visualization of non covalent interactions, which was also published in J. Am. Chem. Soc (over 5600 citations). I also wrote the program to analyze this index, NCIPLOT. The associated paper was published in 2011 in JCTC and it has received over 2600 citations and more than 13000 visits. 

Funded by the Ministry of Spain for one year, I moved to France, to the Laboratoire de Chimie Theorique (LCT), where some months later I earned a CNRS position. In 2015 I defended my HdR. Since 2018 I am team leader of one of the most historical research lines of the LCT, Chemical Interpretation. Last year, I was finalist for the Dirac medal (2nd place) by the WATOC committee. I am part of the European High Pressure Committee and I have received the European High Pressure Award (2013). In 2015 I was elected member of the European Committee of High Pressure, since 2018 I became the Secretary and in 2022 the Chair. Most recently my interests have turned into superconductivity, where we have been able for the first time to introduce an index that describes superconductivity from fast calculations (Nature Communications 12, 5381 (2021)).

During these years I have (will have) given 43 invited talks. Those include 1 plenary at the ICQC (2021) as well as 1 keynote at the IUCr (2020) and 3 invitations to WATOC (2014,2017,2020), one to a Solvay workshop and 1 to a Gordon Conferences. In total, I have published 112 articles (1 Natur Comm, 3 JACS, 1 PRL, 5 Chem Eur J, 1 Chem Sci), as well as two JCTC papers which entered the 10-most-read of their year of publication. I am in the process of publishing a full book along with A. M. Pendás on Quantum Topology for Springer TCCM series. I have also received an invitation for WIREs in 2022.

I had been appointed member of the FWO-Belgium pannel panel for five years, and since September 2020 I have been appointed president of the the FWO Chemistry panel. I have also been involved in the creation of scientific associations (European Committee of Chemical Bonding, Women Under High Pressure). I have also been very involved in the organization and coordination of initiatives to promote women in science. I have created the online database “Women under High Pressure”. This has led to several public conferences and interventions in Conferences and the development of a permanent set of rules to promote women participation in IUCr conferences.