%0 Journal Article
%A Nilsson, Daniel
%A Bozorg, Behruz
%A Mohanty, Sandipan
%A Söderberg, Bo
%A Irbäck, Anders
%T Limitations of field-theory simulation for exploring phase separation: The role of repulsion in a lattice protein model
%J The journal of chemical physics
%V 156
%N 1
%@ 0021-9606
%C Melville, NY
%I American Institute of Physics
%M FZJ-2022-00122
%P 015101 -
%D 2022
%X 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 a loss of ergodicity.
%F PUB:(DE-HGF)16
%9 Journal Article
%$ 34998327
%U <Go to ISI:>//WOS:000739267900004
%R 10.1063/5.0070412
%U https://juser.fz-juelich.de/record/904792