Computational and Quantum Chemistry

2022-04-14 00:35:20 Carbon nanotubes could stabilize energy-rich nitrogen chains – Physics World
https://physicsworld.com/a/carbon-nanotubes-could-stabilize-energy-rich-nitrogen-chains/ Open / Comment

2022-04-13 04:44:58 Chemical Kinetics and Reaction Dynamics Open / Comment

2022-04-11 13:41:35 In a sea of magic angles, 'twistons' keep electrons flowing through three layers of graphene
https://phys.org/news/2022-04-sea-magic-angles-twistons-electrons.html Open / Comment

2022-04-07 21:18:59 https://www.chemistryworld.com/news/this-metal-triangle-seems-to-defy-definition-is-it-aromatic-or-not/4015487.article Open / Comment

2022-04-07 18:53:32 Time-Dependent Long-Range-Corrected Double-Hybrid Density Functionals with Spin-Component and Spin-Opposite Scaling: A Comprehensive Analysis of Singlet–Singlet and Singlet–Triplet Excitation Energies Open / Comment

2022-04-06 13:45:17 https://www.chemistryworld.com/news/microscopy-unveils-piece-by-piece-formation-of-2d-covalent-polymers/4015422.article Open / Comment

2022-04-04 21:25:36 Atomic and Electronic Structure of Solids Open / Comment

2022-04-04 15:38:25 SELFIES and the future of molecular string representations

Artificial intelligence (AI) and machine learning (ML) are expanding in popularity for broad applications to challenging tasks in chemistry and materials science. Examples include the prediction of properties, the discovery of new reaction pathways, or the design of new molecules. The machine needs to read and write fluently in a chemical language for each of these tasks. Strings are a common tool to represent molecular graphs, and the most popular molecular string representation, SMILES, has powered cheminformatics since the late 1980s. However, in the context of AI and ML in chemistry, SMILES has several shortcomings -- most pertinently, most combinations of symbols lead to invalid results with no valid chemical interpretation. To overcome this issue, a new language for molecules was introduced in 2020 that guarantees 100\% robustness: SELFIES (SELF-referencIng Embedded Strings). SELFIES has since simplified and enabled numerous new applications in chemistry. In this manuscript, we look to the future and discuss molecular string representations, along with their respective opportunities and challenges. We propose 16 concrete Future Projects for robust molecular representations. These involve the extension toward new chemical domains, exciting questions at the interface of AI and robust languages and interpretability for both humans and machines. We hope that these proposals will inspire several follow-up works exploiting the full potential of molecular string representations for the future of AI in chemistry and materials science.

https://arxiv.org/abs/2204.00056 Open / Comment

2022-04-03 14:36:06 Elk version 8.4.6 has just been released.

https://sourceforge.net/projects/elk/

This version has several important improvements and bug fixes, including a problem related to restarting TDDFT calculations (tasks 461 and 463). This was discovered by Antonio Sanna.
The second-order optics code has also been completely re-written and now follows the derivation and convention of Sipe and Ghahramani in Phys. Rev. B 48, 11705 (1993). Thanks go to Xavier Gonze for pointing out an error in our non-linear optics paper Phys. Rev. B 67, 165332 (2003). This has now been fixed in the code.
We also added 'batch' calculations as a new feature: this allows a single run of Elk to perform multiple calculations while varying a particular parameter. For example, you can produce an energy-vs-volume plot, or check the convergence of the magnetic moment with respect to the number of k-points, all in one run. See the examples in elk/examples/batch-calculations for details. Note that additional input and output variables will be added upon request.
Ultra-long range calculations have been significantly sped up, thanks to improvements in calculating the long-range density and magnetisation.
Finally, Elk has been recognized with a Community Choice award by SourceForge; thanks to all the users and contributors for making the code as useful as it is, as well as for making the forums a congenial place for everyone. Open / Comment

2022-03-31 22:56:51 https://jobs.sciencecareers.org/job/593856/team-scientist/?TrackID=186762&utm_source=twitterfeed&utm_medium=feed&utm_campaign=14 Open / Comment