Summer Updates To Rowan
Psi4 now available; new structure editor features; conformer search supports metals
Today, we’re excited to share a number of updates to Rowan!
First, Rowan now allows quantum chemical calculations to be run through Psi4. Psi4 is an excellent open-source quantum chemistry program, and adding Psi4 gives us access to a whole suite of modern quantum chemical methods. Through Psi4, we’ve added support for Grimme’s composite/“3c” methods (HF–3c, B97–3c, r2SCAN–3c, and ωB97X–3c). These methods feature highly optimized basis sets and corrections, and are designed to run as quickly as possible while still providing excellent accuracy. Here’s what the authors of the r2SCAN–3c paper have to say about their method:
r2SCAN-3c provides benchmark-accuracy for key properties at a fraction of the cost of previously required hybrid/QZ approaches and is more robust than any other method of comparable cost. This drastically shifts the aforementioned balance between the computational efficiency and accuracy, enabling much larger and/or more thorough screenings and property calculations. In fact, the robustness and broad applicability of r2 SCAN-3c caused us to rethink the very structure of screening approaches.
Here’s what one of us (Corin) wrote about these methods last year:
ωB97X-3c… is among the best-performing DFT methods in general for most benchmarks…. “Classic” DFT has a ton of tunable parameters (functional, basis set, corrections, solvent models, thresholds, and so forth), and people frequently make inefficient or nonsensical choices when faced with this complexity. In contrast, composite methods make principled and opinionated choices for many of these variables, thus giving scientists a well-defined menu of options.
Nevertheless, composite methods still seem underutilized relative to “classic” combinations like B3LYP-D3BJ/6-31G(d)—by putting these methods in Rowan, we hope to make it easier for scientists to run fast, accurate, and optimal calculations.
We’re also adding a few new high-accuracy methods in Psi4: ωB97M–D3BJ and DSD–BLYP–D3BJ. In particular, DSD–BLYP–D3BJ is our first double-hybrid functional and performs best out of all 217 methods surveyed in the GMTKN55 benchmark paper, making it an appealing choice for cases in which maximal accuracy is needed, like benchmarking other methods or correcting single-point energies.
We’ve also updated our 3D structure editor and our conformer search workflow. To make inputting novel structures easier, we’ve added a number of features to our 3D structure editor. To make working with metals possible, the editor now supports the entire periodic table and adding hydrogens up to the tricapped trigonal prismatic geometry. We’ve added a new tool “move selected” that enables click and drag movement of atoms, as well as an “optimize dihedrals” button to quickly minimize clashes. Lastly, the fragment library UI now shows 2D previews of each fragment and fragment adding is much smarter.
Finally, conformer searches now support metals and constraints. To run a conformer search on a metal-containing structure, you’ll need to select GFN2–xTB as your final method and choose either “Careful” or “Meticulous” modes (these modes use CREST to generate conformers instead of RDKit, which doesn’t support metals). Here’s the output of a conformer search on a dysprosium-containing complex (from this paper):
You can add constraints to a conformer search using the constraints form at the bottom of the submit page—this allows for conformer searches on transition states, for instance, which can be very useful. Shown below is a conformer search on a Diels–Alder reaction with a flexible alkyl chain: the forming bonds are frozen to resemble the transition state, and the conformers are superimposed and aligned on the reactive carbons.
We have a lot more in the pipeline, and are always happy to take on new projects to support important research. If there’s something we can do to support your research, please let us know!