Molecular self-organization: Predicting the pattern diversity and lowest energy state of competing ordering motifs

Self-organized monolayers of highly flexible Frechet dendrons were
deposited on graphite surfaces by solution casting. Scanning
tunneling microscopy (STM) reveals an unprecedented variety of
patterns with up to seven stable hierarchical ordering motifs
allowing us to use these molecules as a versatile model system. The
essential molecular properties determined by molecular mechanics
simulations are condensed to a coarse grained interaction-site
model of various chain configurations. In a Monte Carlo approach
with random starting configurations, the experimental pattern
diversity can be reproduced in all facets of the local and global
ordering. Based on an energy analysis of the Monte Carlo and
molecular mechanics modeling, the thermodynamically most stable
pattern is predicted and shown to coincide with the pattern which
dominates the STM images after several hours or upon moderate
heating.