@article{SvaneborgKarimiVarzanehHojdisetal.2016,
  author    = {Svaneborg, Carsten and Karimi-Varzaneh, Hossein Ali and Hojdis, Nils and Fleck, Franz and Everaers, Ralf},
  title     = {Multiscale approach to equilibrating model polymer melts},
  series = {Physical Review E},
  volume    = {94},
  journal   = {Physical Review E},
  number    = {032502},
  publisher = {AIP Publishing},
  address   = {Melville, NY},
  issn      = {2470-0053},
  doi       = {10.1103/PhysRevE.94.032502},
  year      = {2016},
  abstract  = {We present an effective and simple multiscale method for equilibrating Kremer Grest model polymer melts of varying stiffness. In our approach, we progressively equilibrate the melt structure above the tube scale, inside the tube and finally at the monomeric scale. We make use of models designed to be computationally effective at each scale. Density fluctuations in the melt structure above the tube scale are minimized through a Monte Carlo simulated annealing of a lattice polymer model. Subsequently the melt structure below the tube scale is equilibrated via the Rouse dynamics of a force-capped Kremer-Grest model that allows chains to partially interpenetrate. Finally the Kremer-Grest force field is introduced to freeze the topological state and enforce correct monomer packing. We generate 15 melts of 500 chains of 10.000 beads for varying chain stiffness as well as a number of melts with 1.000 chains of 15.000 monomers. To validate the equilibration process we study the time evolution of bulk, collective, and single-chain observables at the monomeric, mesoscopic, and macroscopic length scales. Extension of the present method to longer, branched, or polydisperse chains, and/or larger system sizes is straightforward.},
  language  = {en}
}
@article{SvaneborgKarimiVarzanehHojdisetal.2018,
  author    = {Svaneborg, Carsten and Karimi-Varzaneh, Hossein Ali and Hojdis, Nils and Fleck, Franz and Everaers, Ralf},
  title     = {Kremer-Grest Models for Universal Properties of Specific Common Polymer Species},
  series = {Soft Condensed Matter},
  journal   = {Soft Condensed Matter},
  number    = {1606.05008},
  year      = {2018},
  abstract  = {The Kremer-Grest (KG) bead-spring model is a near standard in Molecular Dynamic simulations of generic polymer properties. It owes its popularity to its computational efficiency, rather than its ability to represent specific polymer species and conditions. Here we investigate how to adapt the model to match the universal properties of a wide range of chemical polymers species. For this purpose we vary a single parameter originally introduced by Faller and M{\"u}ller-Plathe, the chain stiffness. Examples include polystyrene, polyethylene, polypropylene, cis-polyisoprene, polydimethylsiloxane, polyethyleneoxide and styrene-butadiene rubber. We do this by matching the number of Kuhn segments per chain and the number of Kuhn segments per cubic Kuhn volume for the polymer species and for the Kremer-Grest model. We also derive mapping relations for converting KG model units back to physical units, in particular we obtain the entanglement time for the KG model as function of stiffness allowing for a time mapping. To test these relations, we generate large equilibrated well entangled polymer melts, and measure the entanglement moduli using a static primitive-path analysis of the entangled melt structure as well as by simulations of step-strain deformation of the model melts. The obtained moduli for our model polymer melts are in good agreement with the experimentally expected moduli.},
  language  = {en}
}
@article{WallerBraunHojdisetal.2007,
  author    = {Waller, Mark P. and Braun, Heiko and Hojdis, Nils and B{\"u}hl, Michael},
  title     = {Geometries of Second-Row Transition-Metal Complexes from Density-Functional Theory},
  series = {Journal of Chemical Theory and Computation},
  volume    = {3},
  journal   = {Journal of Chemical Theory and Computation},
  number    = {6},
  issn      = {1549-9626},
  doi       = {10.1021/ct700178y},
  pages     = {2234 -- 2242},
  year      = {2007},
  language  = {en}
}