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Two benzene molecules associated by dispersion and electrostatic interactions. T-shaped and parallel-displaced geometries are important low-energy arrangements; a single permanent dipole–dipole model is inadequate.
Edward F. Valeev coauthored calculations of benzene dimer interaction energies using correlated electronic-structure methods. The study compares T-shaped and parallel-displaced minima while examining convergence toward the computational limit.
A small interaction energy can be sensitive to the treatment of electron correlation and to the available basis functions. Assessing convergence is therefore part of the physical interpretation, rather than only a numerical convenience.[ref]
Estimates of the Ab Initio Limit for π–π Interactions: The Benzene Dimer by Mutasem Omar Sinnokrot and others. Computational approach and alternative dimer minima
Portrait of Edward F. Valeev
. External portrait hosted by Virginia Tech, Department of Chemistry. Source.C. David Sherrill coauthored electronic-structure calculations of the benzene dimer. The work compares T-shaped and parallel-displaced arrangements and estimates their interaction energies near the computational basis-set limit.
Two aromatic molecules need not favour a perfectly face-centred stack. Comparing several geometries with electron-correlation methods helps distinguish the effects of electrostatics and dispersion in a noncovalent contact.[ref]
Portrait of C. David Sherrill
. External portrait hosted by Georgia Institute of Technology, School of Chemistry and Biochemistry. Source.Xiaohu Xia investigated symmetry breaking during seeded nanocrystal growth with Younan Xia. Their silver experiments connected reduction kinetics with selection of lower-symmetry growth forms, showing how growth conditions can determine particle shape.[ref]
Symmetry Breaking during Seeded Growth of Nanocrystals by Xiaohu Xia and Younan Xia. 2012, seeded-silver study: reduction kinetics and lower-symmetry growth
Younan Xia coauthored experiments on symmetry breaking during seeded growth of silver nanocrystals. Changing reduction kinetics can favour growth patterns with lower symmetry than the starting seed.
Crystal composition alone therefore does not determine particle shape. The competition between deposition at different sites connects reaction kinetics with nanoscale geometry.[ref]
Symmetry Breaking during Seeded Growth of Nanocrystals by Xiaohu Xia and Younan Xia. Abstract and growth mechanism
Portrait of Younan Xia
. Lu2024. CC0 1.0 Universal Public Domain Dedication. Source usage terms, via Wikimedia Commons. Source.Yujin Jang investigated direct atomic layer deposition of molybdenum disulfide thin films on oxide-covered wafers. Self-limited exposure behaviour connects the deposition chemistry with thickness control, while the reported nanocrystalline microstructure describes the material actually obtained.[ref]
Wafer-scale, conformal and direct growth of MoS2 thin films by atomic layer deposition by Yujin Jang and others. 2016, Applied Surface Science study: exposure saturation and nanocrystalline MoS2
A molecular orbital is a one-electron spatial wavefunction for the combined atomic nuclei of a molecule. For a normalized molecular orbital, the Born rule gives the position probability density , with . The molecular orbital is the amplitude, rather than its squared modulus or a classical trajectory.
A molecular orbital is a one-electron spatial wavefunction for the combined atomic nuclei of a molecule. For a normalized molecular orbital, the Born rule gives the position probability density , with . The molecular orbital is the amplitude, rather than its squared modulus or a classical trajectory.
Andrew J. Peel investigated efficient metalation of unfunctionalized aromatic compounds using mixed copper–lithium amide aggregates. The work connected aggregate composition with exchange behaviour, illustrating why an organometallic reagent's structure in solution can matter to its reactivity.[ref]
A new route for the efficient metalation of unfunctionalized aromatics by Andrew J. Peel and others. 2019, Figures1,4,5 and lithium-rich exchange discussion
A conventional class of chemical elements with properties intermediate between those commonly associated with metals and nonmetals; its membership is not a fundamental sharp boundary.
Electron counting records metal valence electrons plus ligand donations using a declared convention. In ionic counting, subtract metal oxidation state from its group number, then add donor electrons; in neutral counting, combine neutral metal and ligand fragments consistently. An Fe–Fe single bond contributes one electron to the count at each metal.
Pinned article: Introduction to the OurBigBook Project
Welcome to the OurBigBook Project! Our goal is to create the perfect publishing platform for STEM subjects, and get university-level students to write the best free STEM tutorials ever.
Everyone is welcome to create an account and play with the site: ourbigbook.com/go/register. We belive that students themselves can write amazing tutorials, but teachers are welcome too. You can write about anything you want, it doesn't have to be STEM or even educational. Silly test content is very welcome and you won't be penalized in any way. Just keep it legal!
Intro to OurBigBook
. Source. We have two killer features:
- topics: topics group articles by different users with the same title, e.g. here is the topic for the "Fundamental Theorem of Calculus" ourbigbook.com/go/topic/fundamental-theorem-of-calculusArticles of different users are sorted by upvote within each article page. This feature is a bit like:
- a Wikipedia where each user can have their own version of each article
- a Q&A website like Stack Overflow, where multiple people can give their views on a given topic, and the best ones are sorted by upvote. Except you don't need to wait for someone to ask first, and any topic goes, no matter how narrow or broad
This feature makes it possible for readers to find better explanations of any topic created by other writers. And it allows writers to create an explanation in a place that readers might actually find it.
Figure 1. Screenshot of the "Derivative" topic page. View it live at: ourbigbook.com/go/topic/derivativeVideo 2. OurBigBook Web topics demo. Source. - local editing: you can store all your personal knowledge base content locally in a plaintext markup format that can be edited locally and published either:This way you can be sure that even if OurBigBook.com were to go down one day (which we have no plans to do as it is quite cheap to host!), your content will still be perfectly readable as a static site.
- to OurBigBook.com to get awesome multi-user features like topics and likes
- as HTML files to a static website, which you can host yourself for free on many external providers like GitHub Pages, and remain in full control
Figure 2. You can publish local OurBigBook lightweight markup files to either OurBigBook.com or as a static website.
Figure 3. Visual Studio Code extension installation.
Figure 5. . You can also edit articles on the Web editor without installing anything locally. Video 3. Edit locally and publish demo. Source. This shows editing OurBigBook Markup and publishing it using the Visual Studio Code extension. 
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