  Using a modified Lennard-Jones model for elliptic particles and spherical
impurities, we present results of molecular dynamics simulation in two
dimensions. In one-component systems of elliptic particles, we find an
orientation phase transition on a hexagonal lattice as the temperature $T$ is
lowered. It is also a structural one because of spontaneous strain. At low $T$,
there arise three martensitic variants due to the underlying lattice, leading
to a shape memory effect without dislocation formation. Thermal hysteresis, a
minimum of the shear modulus, and a maximum of the specific heat are also found
with varying $T$. With increasing the composition $c$ of impurities, the three
kinds of orientation domains are finely divided, yielding orientation-strain
glass with mesoscopically ordered regions still surviving. If the impurities
are large and repulsive, planar anchoring of the elliptic particles occurs
around the impurity surfaces. If they are small and attractive, homeotropic
anchoring occurs. Clustering of impurities is conspicuous. With increasing the
anchoring power and/or the composition of the impurities, positional disorder
can also be enhanced. We also investigate the rotational dynamics of the
molecular orientations.
