Nav: Home

Theoretical physicists unveil one of the most ubiquitous and elusive concepts in chemistry

July 01, 2019

Even if we study them at school, oxidation numbers have so far eluded any rigorous quantum mechanical definition. A new SISSA study, published in Nature Physics, reverses this state of affairs by providing such a definition, based on the theory of topological quantum numbers, which was honoured with the 2016 Nobel prize in Physics awarded to Thouless, Haldane and Kosterlitz. This result, combined with recent advances in the theory of transport achieved at SISSA, paves the way to an accurate, yet tractable, numerical simulation of a broad class of materials that are important in energy-related technologies and planetary sciences.

Every undergraduate student in the natural sciences learns how to associate an integer oxidation number to a chemical species participating in a reaction. Unfortunately, the very concept of oxidation state has thus far eluded a rigorous quantum mechanical definition, so that no method was known until now to compute oxidation numbers from the fundamental laws of nature, let alone demonstrate that their use in the simulation of charge transport does not spoil the quality of numerical simulations. At the same time, the evaluation of electric currents in ionic conductors, which is required to model their transport properties, is presently based on a cumbersome quantum-mechanical approach that severely limits the feasibility of large-scale computer simulations. Scientists have lately noticed that a simplified model where each atom carries a charge equal to its oxidation number may give results in surprising good agreement with rigorous but much more expensive approaches. By combining the new topological definition of oxidation number with the so-called "gauge invariance" of transport coefficients, recently discovered at SISSA, Federico Grasselli and Stefano Baroni proved that what was considered a mere coincidence stands in fact on solid theoretical grounds, and that the simple integer-charge model captures the electrical transport properties of ionic conductors without any approximations.

Besides solving a fundamental conundrum in condensed matter physics, this result, achieved within the framework of the European MAX Centre of Excellence for supercomputing applications, also represents a breakthrough for applications, enabling computationally feasible quantum simulations of charge transport in ionic systems of paramount importance in energy-related technologies, in the automotive and telecommunications sectors, as well as in planetary sciences. Such applications range from the ionic mixtures adopted in electrolytic cells and heat exchangers in power plants, to solid-state-electrolyte batteries for electric cars and electronic devices, and even to the conducting exotic phases of water occurring in the interior of icy giants, which are supposed to be related to the origin of the magnetic fields in these planets.
-end-


Scuola Internazionale Superiore di Studi Avanzati

Related Planetary Sciences Articles:

The strange orbits of 'Tatooine' planetary disks
Astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA) have found striking orbital geometries in protoplanetary disks around binary stars.
SDSU astronomers pinpoint two new 'Tatooine' planetary systems
The discoveries include the first circumbinary planet revealed by observations from NASA's TESS mission, which will search nearly the entire sky.
Numerous polar storms on Saturn analyzed by the UPV/EHU's Planetary Sciences Group
Nature Astronomy has published the results of the research conducted by the Planetary Sciences Group at the UPV/EHU-University of the Basque Country; the group is led by Professor Agustín Sánchez-Lavega and their research deals with the monitoring they carried out on a series of huge, long-lived storms that took place on the planet Saturn.
Planetary collisions can drop the internal pressures in planets
A new study finds that collisions between planetary bodies, such as the event that created Earth's moon, could abruptly drop the planet's internal pressure.
When it comes to planetary habitability, it's what's inside that counts
Which of Earth's features were essential for the origin and sustenance of life?
Massive collision in the planetary system Kepler 107
Two of the planets which are orbiting the star Kepler 107 could be the result of an impact similar to that which affected the Earth to produce the moon.
ASU scientists study organization of life on a planetary scale
In astrobiology, there is an increasing interest in whether life as we know it is a quirk of the particular evolutionary history of the Earth or, instead, if life might be governed by more general organizing principles.
Planetary collision that formed the moon made life possible on Earth
Most of Earth's life-essential elements probably arrived with the planetary collision that produced the moon.
Planetary boundaries for antibiotic and pesticide resistance identified
Researchers have now published the first estimates of antibiotic and pesticide 'planetary boundaries' in the journal Nature Sustainability.
Some planetary systems just aren't into heavy metal
Small planetary systems with multiple planets are not fans of heavy metal -- think iron, not Iron Maiden -- according to a new Yale University study.
More Planetary Sciences News and Planetary Sciences Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Listen Again: Reinvention
Change is hard, but it's also an opportunity to discover and reimagine what you thought you knew. From our economy, to music, to even ourselves–this hour TED speakers explore the power of reinvention. Guests include OK Go lead singer Damian Kulash Jr., former college gymnastics coach Valorie Kondos Field, Stockton Mayor Michael Tubbs, and entrepreneur Nick Hanauer.
Now Playing: Science for the People

#562 Superbug to Bedside
By now we're all good and scared about antibiotic resistance, one of the many things coming to get us all. But there's good news, sort of. News antibiotics are coming out! How do they get tested? What does that kind of a trial look like and how does it happen? Host Bethany Brookeshire talks with Matt McCarthy, author of "Superbugs: The Race to Stop an Epidemic", about the ins and outs of testing a new antibiotic in the hospital.
Now Playing: Radiolab

Dispatch 6: Strange Times
Covid has disrupted the most basic routines of our days and nights. But in the middle of a conversation about how to fight the virus, we find a place impervious to the stalled plans and frenetic demands of the outside world. It's a very different kind of front line, where urgent work means moving slow, and time is marked out in tiny pre-planned steps. Then, on a walk through the woods, we consider how the tempo of our lives affects our minds and discover how the beats of biology shape our bodies. This episode was produced with help from Molly Webster and Tracie Hunte. Support Radiolab today at Radiolab.org/donate.