Mikael Lund - Anisotropic Interactions and Intermolecular Pose Exploration using Subdivided Spheres

Описание: This lecture was part of the Workshop on "Charged Soft Matter: Bridging Theory and Experiment" held at the ESI September 8 - 12, 2025.
Understanding interactions between large, aspherical macromolecules such as proteins and colloids require careful consideration of angular dependent forces. Surface charge anisotropy, for example, leads to a surprising non-monotonic ionic strength dependence of measured osmotic second virial coefficient for globular proteins. We review a number of recent experimental and computational findings where intermolecular anisotropy is manifested. To fully bridge theory and experiment, large-scale computer simulations of many macromolecules are often needed. Exploring the vast configurational space is however computationally intensive and large speedups can be gained with high-dimensional lookup tables. We present a new approach to such tables using subdivided spheres in order to construct 6D tables, storing angular dependent energies between protein pairs. In addition to offering convenient interpolation, the tables have the unintended, but pleasant property that they allows for explicit evaluation of the configurational integral and derived twobody thermodynamics. We use this to explore protein osmotic virial coefficients using the recent Calvados coarse grained model and light-scattering experiments. Software for calculating virial coefficients and potential of mean force is available at https://github.com/mlund/duello.