I will introduce some general aspects and problems about simulating
biomolecules and the necessity of a coarse-grained model for
biomolecules that allows to achieve the length and time scale,
experimentally observed, without loosing the link with an atomistic
description. I will present an approach to generate transferable
non-bonded interaction potentials and its application on a simple model
system. I will also address the importance of conformational flexibility
in coarse-grained model and present the work done to develop a flexible
model for a dipeptide self-aggregating system.