Limitations of field-theory simulation for exploring phase separation: The role of repulsion in a lattice protein model

Summary, in English

Field-theory simulation by the complex Langevin method offers an alternative to conventional sampling techniques for exploring the forces driving biomolecular liquid–liquid phase separation. Such simulations have recently been used to study several polyampholyte systems. Here, we formulate a field theory corresponding to the hydrophobic/polar (HP) lattice protein model, with finite same-site repulsion and nearest-neighbor attraction between HH bead pairs. By direct comparison with particle-based Monte Carlo simulations, we show that complex Langevin sampling of the field theory reproduces the thermodynamic properties of the HP model only if the same-site repulsion is not too strong. Unfortunately, the repulsion has to be taken weaker than what is needed to prevent condensed droplets from assuming an artificially compact shape. Analysis of a minimal and analytically solvable toy model hints that the sampling problems caused by repulsive interaction may stem from loss of ergodicity.

• Author: Daniel Nilsson; Behruz Bozorg; Sandipan Mohanty; Bo Söderberg; Anders Irbäck
• Department/s: eSSENCE: The e-Science Collaboration; Computational Biology and Biological Physics - Has been reorganised; Computational Science for Health and Environment
• Publishing year: 2022-01-04
• Language: English
• Publication/Series: The Journal of chemical physics
• Volume: 156
• Issue: 1
• Links: http://dx.doi.org/10.1063/5.0070412
• Document type: Journal article
• Publisher: American Institute of Physics (AIP)
• Topic: Other Physics Topics; Biophysics
• Status: Published
• Research group: Computational Science for Health and Environment
• ISBN/ISSN/Other: ISSN: 0021-9606