The Kitchin Research Group

In this work we show that prediction errors from graph neural networks for related atomistic systems tend to be correlated, and as a result the differences in energy are more accurate than the absolute energies. This is similar to what is observed in DFT calculations where systematic errors also cancel in differences. We show this quantitatively through differences of systems with systematically different levels of similarity. This article is part of the Special Collection: 2023 JCP Emerging Investigators Special Collection.

@article{ock-2023-beyon-indep,
  author =       {Janghoon Ock and Tian Tian and John Kitchin and Zachary
                  Ulissi},
  title =        {Beyond Independent Error Assumptions in Large {GNN} Atomistic
                  Models},
  journal =      {The Journal of Chemical Physics},
  volume =       158,
  number =       21,
  pages =        {nil},
  year =         2023,
  doi =          {10.1063/5.0151159},
  url =          {http://dx.doi.org/10.1063/5.0151159},
  DATE_ADDED =   {Sun Sep 24 14:53:46 2023},
}

Copyright (C) 2023 by John Kitchin. See the License for information about copying.

org-mode source

Org-mode version = 9.7-pre

We have a new publication out! In this work we show how to use classification algorithms to find boundaries in science and engineering applications. These applications come up all over the place, for example you may want to know what compositions phase separate, and which ones are single phase, or what conditions lead to degradation and which ones don't. You might want to know which operating parameters have desirable properties, and which don't. In this work we show how to efficiently find the boundaries between these regions using active learning and a classifier. We show that this approach is generally better (more accurate and fewer experiments) than doing a dense grid search.

@article{bhat-2023-sequen-sampl,
  author =       {Maya Bhat and John R. Kitchin},
  title =        {Sequential Sampling Methods for Finding Classification
                  Boundaries in Engineering Applications},
  journal =      {Industrial \& Engineering Chemistry Research},
  volume =       {n/a},
  number =       {n/a},
  pages =        {n/a},
  year =         2023,
  doi =          {10.1021/acs.iecr.3c02362},
  url =          {http://dx.doi.org/10.1021/acs.iecr.3c02362}
}

Check out the Youtube video summary here:

Copyright (C) 2023 by John Kitchin. See the License for information about copying.

org-mode source

Org-mode version = 9.7-pre

Solving inverse problems, where we know what outputs we want from a model and seek the inputs that provide them, is a difficult task. A conventional approach to this problem is to use a nonlinear program (NLP) solver to iteratively find the inputs for a specific output. If you seek a desired output space, then you must solve the NLP many times to map out the corresponding input space. This is often expensive, and tedious to perform. In this work, we demonstrate a new approach to solving this problem that avoids the NLP formulation, and is faster. The idea is simple; we compute a system of differential equations that maps how the input space changes with the output space. Then from a single known point we can integrate a path in the output space to automatically trace the corresponding path in the input space! We compute the system of differential equations using automatic differentiation, and the implicit derivative theorem. We show two examples of this using a steady state continuously stirred tank reactor, which is a set of nonlinear algebraic equations that define the output space from input variables, and another plug flow reactor where the output space is defined by a set of differential equations that must be numerically integrated. In both cases we use automatic differentiation to define the system of ODEs that relate outputs and inputs, and show that the path integration method developed here is as accurate and faster than even the best NLP approach. The idea in this paper is general and applicable to many other systems, not just chemical reactors.

@article{alves-2023,
  author =       {Alves, Victor and Kitchin, John R. and Lima, Fernando V.},
  title =        {An inverse mapping approach for process systems engineering
                  using automatic differentiation and the implicit function
                  theorem},
  journal =      {AIChE Journal},
  year =         2023,
  volume =       {n/a},
  number =       {n/a},
  pages =        {e18119},
  keywords =     {automatic differentiation, implicit function theorem, inverse
                  mapping, inverse problems, process systems engineering},
  doi =          {10.1002/aic.18119},
  url =
                  {https://aiche.onlinelibrary.wiley.com/doi/abs/10.1002/aic.18119}
}

Copyright (C) 2023 by John Kitchin. See the License for information about copying.

org-mode source

Org-mode version = 9.5.5

Suppose you want to explore metal oxides as potential water oxidation electrocatalysts. There are many steps to do this. You can use databases of materials to get compositions and structures, but for each one you have to determine the ground state structure, including magnetic states, for each bulk structure, and filter out bulk materials that are not stable under water oxidation conditions. Then, using the remaining structures you have to construct slabs and determine which surfaces are likely to be stable, and most relevant. After that you have to compute adsorption energies on those surfaces to see which surfaces have the most relevant reactivity (while also being stable). This results in hundreds to thousands of calculations that depend on each other in important ways. It is very useful to use software workflow tools to facilitate and manage this process. In this paper we develop a workflow like this for exploring metal oxides for water oxidation. The software is open source and available at https://github.com/ulissigroup/wherewulff.

The paper is free to read for 6 months at https://pubs.acs.org/doi/10.1021/acs.jcim.3c00142.

@article{sanspeur-2023,
  author = {Rohan Yuri Sanspeur and Javier Heras-Domingo and John R. Kitchin and Zachary Ulissi},
  title = {wherewulff: a Semiautonomous Workflow for Systematic Catalyst Surface Reactivity Under Reaction Conditions},
  journal = {Journal of Chemical Information and Modeling},
  volume = {nil},
  number = {nil},
  pages = {nil},
  year = {2023},
  doi = {10.1021/acs.jcim.3c00142},
  url = {http://dx.doi.org/10.1021/acs.jcim.3c00142},
  DATE_ADDED = {Sun Apr 16 09:17:23 2023},
}

Copyright (C) 2023 by John Kitchin. See the License for information about copying.

org-mode source

Org-mode version = 9.5.5

Finding new ways to make hydrogen with renewable energy and renewable feedstocks using earth abundant materials remains a challenge in catalysis today. Metal nanoparticles are common heterogeneous catalysts for hydrogen production, and their properties can often be improved by using multiple metals at a time. In this work we show a high-throughput experimental approach to discovering a ternary alloy catalyst containing earth abundant metals that is more active at producing hydrogen than any of the pure metals it is made of. It a surprising discovery because these metals are not typically miscible, and they do not form a well characterized material, but rather a distribution of particle sizes and compositions.

@article{bhat-2023-high-throug,
  author = {Maya Bhat and Zoe C Simon and Savannah Talledo and Riti Sen and Jacob H. Smith and Stefan Bernhard and Jill E Millstone and John R Kitchin},
  title = {High Throughput Discovery of Ternary Cu-Fe-Ru Alloy Catalysts for Photo-Driven Hydrogen Production},
  journal = {Reaction Chemistry \& Engineering},
  volume = {nil},
  number = {nil},
  pages = {nil},
  year = {2023},
  doi = {10.1039/d3re00059a},
  url = {http://dx.doi.org/10.1039/D3RE00059A},
  DATE_ADDED = {Sat Apr 15 07:55:55 2023},
}

Copyright (C) 2023 by John Kitchin. See the License for information about copying.

org-mode source

Org-mode version = 9.5.5