A multiple time step scheme for multiresolved models of Macromolecules

Abstract

In hybrid particle models where coarse-grained beads and atoms are used simultaneously, two clearly separate time scales are mixed. If such models are used in molecular dynamics simulations, a multiple time step (MTS) scheme can therefore be used. In this manuscript, we propose a simple MTS algorithm which approximates for a specific number of integration steps the slow coarse-grained bead-bead interactions with a Taylor series approximation while the atom-atom ones are integrated every time step. The procedure is applied to a previously developed hybrid model of a melt of atactic polystyrene (di Pasquale, Marchisio, and Carbone, J. Chem. Phys. 2012, 137, 164111). The results show that structure, local dynamics, and free diffusion of the model are not altered by the application of the integration scheme which can confidently be used to simulate multiresolved models of polymer melts.

A multiscale approach to model hydrogen bonding: The case of polyamide

“…5,49,50 We have shown that the local dynamics of a multiresolved polymer chain is indeed affected (i.e., the chain moves faster) at short time scales by the presence of fast-moving beads bonded to slower atoms. 38 It is then possible that such speed up weakens the HB network and a detailed analysis of its dynamics is reported below. It is important to notice however that although using Eq.…”

“…The work in this paper used an integration time step of 1 fs for both the CG and atomistic parts of the system; however, work has been done which allows the atomistic and CG portions of a hybrid scale model to be treated using its "native" time step. 38 If implemented, this would again increase the speed of the hybrid model and help bridge the gap towards the CG model's speed.…”

“…31 Recently, we have also developed a simple multiple time step scheme which can take advantage of the intrinsic division between different length and time scales in the dynamics of these kind of models. 38 In this contribution, we develop an AA-CG dual resolved model for a polymer system, polyamide, which has a welldefined HB network and test its ability to correctly reproduce the thermodynamics and dynamical properties of the HBs. In developing the hybrid model, we follow our strategy of mixing a structural based CG model with the AA one used to develop the former but here we also include new features as charge-charge interactions between atoms and two different thermostats to treat separately atoms and beads.…”

Scalability of Coarse‐Grained Potentials Generated from Iterative Boltzmann Inversion for Polymers: Case Study on Polycarbonates

“…The aim is to access the experimental length and time scales that are normally much larger than those accessible to standard atomistic models . There are numerous reports where scientists try to link the atomistic to mesoscopic scales and then back to the atomistic scale by reverse mapping–or even to merge atoms and coarse‐grained beads in a single model ,. A common and widely used way to address this issue is to develop CG models from atomistic systems by merging groups of chemically connected atoms into beads (or superatoms).…”

Multi-resolution dimer models in heat baths with short-range and long-range interactions

“…which, for our choice of oscillators' frequencies and interaction terms (41), satisfies κ ∞ (τ ) = 0 for τ > 0 and κ ∞ (0) = ∞. Thus the limiting kernel is a multiple of the Dirac delta function.…”