Frank-Kasper Phases of Diblock Copolymer Melts Studied with the DPD Model

Here we present reciprocal-space self-consistent field (SCF) calculations of the Frank-Kasper (FK) phases formed by diblock copolymer (DBC) melts based on the model used in dissipative particle dynamics (DPD) simulations, following the method of Matsen (Macromolecules 45, 8502 (2012)). Comparisons with the SCF results based on the “standard” model (i.e., incompressible melts of continuous Gaussian chains with the Dirac d-function interaction) clearly reveal the effects of model differences (i.e., discrete Gaussian chains, finite-range interactions, and compressibility) on the stability of FK phases. This also enables us to unambiguously quantify using DPD simulations the fluctuation/correlation effects inherently neglected by the SCF theory, which are important to the low-molecular weight DBCs forming such phases in experiments.