  The dissipative particle dynamics (DPD) simulation method has been shown to
be a promising tool to study self-assembly of soft matter systems. In
particular, it has been used to study block copolymer (BCP) self-assembly.
However, previous parametrizations of this model are not able to capture most
of the rich phase behaviors of block copolymers in thin films nor in directed
self-assembly (chemoepitaxy or graphoepitaxy). Here we extend the applicability
of the DPD method for BCPs to make it applicable to thin films and directed
self-assembly. Our new reparametrization is able to reproduce the bulk phase
behavior, but also manages to predict thin film structures obtained
experimentally from chemoepitaxy or graphoepitaxy. A number of different
complex structures, such as bilayer nanomeshes, 90{\deg} bend structures,
circular cylinders/lamellae and Frank-Kasper phases directed by trenches, post
arrays or chemically patterned substrate have all been reproduced in this work.
This reparametrized DPD model should serves as a powerful tool to predict BCP
self-assembly, especially in some complex systems where it is difficult to
implement SCFT.
