Exchange of macromolecules and colloids in a dense medium: A molecular simulation method.

This study presents a molecular simulation method to insert and delete large objects, such as macromolecules or colloids, in a dense medium. This method is based on an extended Hamiltonian formulation that allows extra spatial dimensions for the atoms of the inserted object. By actively controlling the extra coordinates of the atoms, this method can prevent fatal instability in principle and is as efficient as FADE. Its implementation is a straightforward extension of a standard molecular simulation algorithm. This method is first applied successfully to three molecular systems: Ar liquid, linear polymer melts, and a carbon nanotube in an Ar solvent. Unlike FADE, this method does not require extensive pre-testing of each material system to obtain control parameters that depend less on the material properties. Insertion of a nanosized solid sphere, most disruptive to the potential field of the base medium among the objects, is also conducted. This method enables a robust mass exchange in molecular simulation, especially for macromolecules or colloids in complex molecular systems. [ABSTRACT FROM AUTHOR]