By molecular modeling we demonstrate that the nematic long-range order
discovered in bent-core liquid crystal systems should reveal further spatially
homogeneous phases. Two of them are identified as a tetrahedratic nematic
(NT) phase with D2d symmetry and a chiral tetrahedratic nematic
(NT∗) phase with D2 symmetry. These new phases were found for a lattice
model with quadrupolar and octupolar anisotropic interactions using Mean Field
theory and Monte Carlo simulations. The phase diagrams exhibit tetrahedratic
(T), NT and NT∗ phases, in addition to ordinary isotropic (I),
uniaxial nematic (NU) and biaxial nematic (NB) phases. To our knowledge,
this is the first molecular model with spontaneous chiral symmetry breaking in
non-layered systems.Comment: 12 pages, 4 figures, submitted for publicatio