Field-accelerated Monte Carlo simulations in the canonical and isothermal-isobaric ensembles

We propose and develop a mesoscale particle-in-field simulation scheme, the Field-Accelerated Monte Carlo (FAMC) method, for speeding up particle-based continuum Monte Carlo (CMC) simulations based on soft interacting models. A key difference from the previously reported single-chain-in-mean-field method [K. C. Daoulas and M. Müller, J. Chem. Phys. 125, 184904 (2006)] is that the auxiliary fields in FAMC are constructed based on lattice-independent interacting potentials. As a result, FMAC simulations asymptotically approach CMC simulations with an increase in the lattice resolution of the auxiliary fields and are able to reproduce structural properties at morphology, conformation, and segment levels. A suite of schemes for computing and updating the auxiliary fields in FAMC simulations are developed in tandem to further enhance the computational efficiency of the method. The capacity of the FAMC method is demonstrated and tested against CMC simulations in simulating polymer solutions with explicit solvent under the canonical (nVT) ensemble and stress-free mircophase formation under the isothermal-isobaric (nPT) ensemble. In both cases, FAMC simulations reproduce structure properties with quantitative accuracy at a fraction of the computational cost.