Complex Electronic Structure Of Benzene Finally Explained After 200 Years

Researchers finally bring us some delightful news on the complex electronic structure of Benzene nearly 200 years after we discovered the molecule. Now, this result paved a way for having future designs of solar cells, organic light-emitting diodes and other next-gen technologies.

We have settled the debate that has been raging since the 1930s. This discovery has now given us important implications for the future development of optoelectronic materials,  many of which are based on Benzene. These optoelectronic materials have an eminent role in producing renewable energy and in telecommunications tech.

The atomic structure of Benzene is undoubtedly understood. It is a flat hexagonal structure and is an important component of DNA, proteins, wood, and petroleum.

The main knotty part comes when one considers the molecules’ 42 electrons. The complexity and controversy arise when it was found that the electrons exist in a state comprising 126 dimensions with each electron having 3 dimensions each depending on another. This dependency makes it complex and nearly not possible to break this down to 42 independent three-dimensional functions.

Analyzing this complex electronic structure of Benzene proved it was impossible, meaning that the precise behavior of electrons couldn’t be understood. Because of which we could never fully understand the stability of the molecule in various fields. These complications have led to debates so far.

Two ideologies that Benzene could follow were the Valence Bond theory with localized electrons or Molecular Orbital theory with delocalized electrons. None of them could seem to fit it.

However, scientists led by Timothy Schmidt from the ARC Centre of Excellence in Exciton Science and UNSW Sydney have unraveled the mystery–and the results came as a surprise. They published this in the journal Nature Communications.

Interpreting the electronic structure in terms of orbitals ignores that the wave function is antisymmetric upon interchange of like-spins,” the researchers wrote in their paper. “Molecular orbitals do not provide an intuitive description of electron correlation.”

This was possible with a technique found by the team. This technique called dynamic Voronoi Metropolis sampling, and it uses an algorithmic approach to visualize the wave functions of a multiple-electron system.

This separates the electron dimensions into separate tiles in a Voronoi diagram, with each of the tiles corresponding to electron coordinates, allowing the team to map the wave function of all 126 dimensions.

Schmidt added that the result they found was something that chemists would not think about Benzene. “The electrons with what’s known as up-spin double-bonded, where those with down-spin single-bonded, and vice versa. Essentially, it reduces the energy of the molecule, making it more stable, by getting electrons, which repel each other, out of each other’s way.” said Schmidt.

“But we also show how to inspect what we call electron correlation – how the electrons avoid each other. This is almost always ignored qualitatively, and only invoked for calculations where only the energy is used, not the electronic behavior.”

They have published the research in Nature Communications.


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