Performing coarse-grained molecular dynamics simulations in the isothermal,isobaric ensemble

Many systematically derived coarse-grained (CG) models for molecular dynamics (MD) simulations lack the ability to accurately describe the cohesive interactions between CG particles. As a consequence the volume of the CG system expands, if the simulations are performed at the same external pressure as during the reference simulations. To compensate for this effect Das and Andersen2 proposed to extend the classical Hamiltonian of the system with a volume dependent potential. This additional term dampens the barostat equations of motion and facilitates the performance of CG simulations at the same state point in the isothermal, isobaric ensemble as during the reference simulations.

The idea of Das and Andersen has been picked up by Dunn and Noid2,3 to develop CG models for mixtures of alkanes. Compared to their work, we present a simpler approach to parameterize the volume dependent potential and show that only one set of non-bonded pair potentials is sufficient to develop CG models which are applicable at different temperatures and concentrations.4,5

1 Das et al., J. Chem. Phys., 2010, 132, 164106

2 Dunn et al., J. Chem. Phys., 2015, 143, 243148

3 Dunn et al., J. Chem. Phys., 2016, 144, 204124

4 Rosenberger et al., Phys. Chem. Chem. Phys., 2018, 20, 6617

5 Rosenberger et al., Phys. Rev. E., 2019, 99, 053308