When thinking about science, I find it helpful to divide computations into two categories: models and oracles.

—Richard Hamming What’s the difference between science and engineering? Five years ago, I would have said something along the lines of “engineers study known unknowns, scientists study unknown unknowns” (with apologies to Donald Rumsfeld), or made a distinction between expanding the frontiers of knowledge (science) and settling already-explored territory (engineering). These thoughts seem broadly consistent with what others think.

Every year, our group participates in a “Paper of the Year” competition, where we each nominate five papers and then duke it out in a multi-hour debate.

For almost all Hartree–Fock-based computational methods, including density-functional theory, the rate-limiting step is calculating electron–electron repulsion.

While looking over papers from the past year, one theme in particular stood out to me: meta-optimization, or optimizing how we optimize things.

Note: old versions of this post lacked a discussion of S _N 2. I've added an appendix which remedies this. In “The Rate-Limiting Span,” I discussed how thinking in terms of the span from ground state to transition state, rather than in terms of elementary steps, can help prevent conceptual errors. Today, I want to illustrate why this is important in the context of a little H/D KIE puzzle.

Last January, I aimed to read 50 books in 2022. I got through 32, which is at least more than I read in 2021. There’s been a bit of discourse around whether setting numerical reading goals for oneself is worthwhile or counterproductive.

A technique that I’ve seen employed more and more in computational papers over the past few years is to calculate Boltzmann-weighted averages of some property over a conformational ensemble.

Today I want to engage in some shameless self-promotion and highlight how cctk, an open-source Python package that I develop and maintain with Eugene Kwan, can make conformational searching easy.

Since my previous “based and red pilled” post seems to have struck a nerve, I figured I should address some common objections people are raising.

¹³ C NMR is, generally speaking, a huge waste of time. This isn’t meant to be an attack on carbon NMR as a scientific tool; it’s an excellent technique, and gives structural information that no other methods can. Rather, I take issue with the requirement that the identity of every published compound be verified with a ¹³ C NMR spectrum. Very few ¹³ C NMR experiments yield unanticipated results.