The multiscale coarse-graining method. V. Isothermal-isobaric ensemble.

Area of Science:

• Computational Chemistry
• Statistical Mechanics
• Materials Science

Background:

• The multiscale coarse-graining (MS-CG) method derives effective potentials for coarse-grained (CG) models from atomistic simulations.
• Existing MS-CG methods are well-established for the canonical ensemble (constant volume).

Purpose of the Study:

• To develop and validate an MS-CG method applicable to the isothermal-isobaric ensemble (constant pressure and temperature).
• To enable CG models to accurately reproduce system volume fluctuations.

Main Methods:

• Formulated an MS-CG approach incorporating an explicit volume-dependent term into the CG potential energy function.
• Applied the method to constant pressure simulations of a model solution.
• Validated the transferability of derived potentials to larger systems.

Main Results:

• The proposed MS-CG method successfully generates correct volume fluctuations and site distribution functions.
• Both volume-dependent and coordinate-dependent parts of the effective potential were found to be transferable.
• The theory is applicable to systems with isotropic volume fluctuations and no intramolecular constraints.

Conclusions:

• The developed MS-CG method provides a statistically robust framework for constant pressure simulations.
• This advancement allows for more accurate and efficient modeling of systems where volume changes are significant.
• The transferability of derived potentials enhances the predictive power of CG models in materials science and chemistry.