Redox Potentials, Education, and Documentation

more efficient + accurate ways to compute redox potentials; using Rowan in the classroom; improving our documentation

Better Methods for Redox Potential Prediction

Back in May, we launched our redox-potential-prediction workflow with two methods: “rapid” (which used GFN2-xTB calculations), and “careful” (which used B3LYP/6-31+G(d) calculations). Since then, we’ve upgraded our DFT offerings a lot: we added Psi4 as an engine, and now use modern “composite” methods like r²SCAN-3c and ωB97X-3c as our defaults for most workflows.

We’ve had some users report redox potentials that were poorly predicted with our existing workflow, and so we decided to update the redox potential workflow to allow for increased accuracy and efficiency. Here’s the new modes, which now match those from most other workflows:

• Reckless: GFN2-xTB/CPCM-X(MeCN) // GFN-FF, with an empirical shift of 4.846 V applied as reported by Neugebauer et al. This is essentially the old “rapid” mode.

• Rapid: r²SCAN-3c/COSMO(MeCN) // GFN2-xTB. This should be faster and more accurate than the old “careful” mode, since only a single-point calculation is done with DFT.

• Careful: ωB97X-3c/COSMO(MeCN) // r²SCAN-3c. ωB97X-3c was recently highlighted as a particularly effective DFT method for redox potential prediction.

• Meticulous: ωB97M-D3BJ/def2-TZVPPD/COSMO(MeCN) // ωB97X-3c // r²SCAN-3c.

These methods now follow established best practices for high-level computational chemistry, and should lead to better accuracy and efficiency in almost every case, particularly for tricky systems like metal complexes. Try it out!

Using Rowan For Classes

Computation has become a cornerstone of modern chemical research, both in academia and industry, but incorporating modern computations into chemical education can be pretty difficult. Rowan makes it easy to incorporate computations into existing curricula: our web-native platform reduces the technical burden on professors and teaching assistants, making it easy for students to explore computation on their own, and our high-level workflows make it straightforward to connect calculations to topics in the course materials.

We’ve worked with three different classes to try out Rowan this semester, both at the undergraduate and graduate level, and are excited to expand to more classes in the spring semester. We’re introducing a low-cost paid tier for classes that want to incorporate computation deeply, but Rowan's free tier is enough for introducing students to computational chemistry. If you’re interested, you can read more about this on our new education page; reach out if you want to discuss more!

Improving Our Documentation

We’ve been conducting a lot of user meetings, and something that we’ve heard a lot recently is that our documentation needs to be way better. While six months ago Rowan was very simple, Rowan is now becoming much more capable and complex, and it’s easy to get confused by a growing number of poorly documented features—particularly for scientists without previous experience in computational chemistry.

To address this, we’re working on creating comprehensive documentation for all of our different workflows, settings, and features. Our goal is to make it simple for scientists who’ve never run computations before to get started and generate high-quality and useful results, as well as clearly explaining everything that’s going on behind the scenes for computational experts.

This project will take us a while, but as a first step we’re (1) updating our documentation site and (2) launching a set of tutorial videos that explain what each workflow means and how to run them. Here’s a few highlights:

• Conformational searching (video, transcript; 5 minute runtime)

• Running an optimization and frequency calculation (video, transcript; 3 minute runtime)

• Global electrophilicity prediction (video, transcript; 5 minute runtime)

• Fukui indices (video, transcript; 5 minute runtime)

• ADME/tox prediction (video, transcript; 9 minute runtime)

We’ll have more videos live soon (we’re currently rate-limited on Youtube), and plan to record more, as well as adding more in-depth scientific explanations to our site. Please let us know if there’s anything in particular that you’d like to be better documented!