We reconsider the structure-based route to coarse graining in which the coarse-grained model is defined in such a way to reproduce some distribution functions of the original system as accurately as possible. We consider standard expressions for pressure and chemical potential applied to this family of coarse-grained models with density-dependent interactions and show that they only provide approximations to the pressure and chemical potential of the underlying original system. These approximations are then carefully compared in two cases: we consider a generic microscopic system in the low-density regime and polymer solutions under good-solvent conditions. Moreover, we show that the state-dependent potentials depend on the ensemble in which they have been derived. Therefore, care must be used in applying canonical state-dependent potentials to predict phase lines, which is typically performed in other ensembles. (C) 2013 AIP Publishing LLC.
Predicting the thermodynamics by using state-dependent interactions / Giuseppe, D'Adamo; Pelissetto, Andrea; Carlo, Pierleoni. - In: THE JOURNAL OF CHEMICAL PHYSICS. - ISSN 0021-9606. - STAMPA. - 138:23(2013), p. 234107. [10.1063/1.4810881]
Predicting the thermodynamics by using state-dependent interactions
PELISSETTO, Andrea;
2013
Abstract
We reconsider the structure-based route to coarse graining in which the coarse-grained model is defined in such a way to reproduce some distribution functions of the original system as accurately as possible. We consider standard expressions for pressure and chemical potential applied to this family of coarse-grained models with density-dependent interactions and show that they only provide approximations to the pressure and chemical potential of the underlying original system. These approximations are then carefully compared in two cases: we consider a generic microscopic system in the low-density regime and polymer solutions under good-solvent conditions. Moreover, we show that the state-dependent potentials depend on the ensemble in which they have been derived. Therefore, care must be used in applying canonical state-dependent potentials to predict phase lines, which is typically performed in other ensembles. (C) 2013 AIP Publishing LLC.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.