Ground state and spectral properties across a charge density wave transition in a triangular lattice spinless fermion model

We study ground state properties and particle excitation spectra across a commensurate charge density wave transition in a system of strongly interacting fermions, using series expansion methods and mean-field theory. We consider a 1/3-filled system of spinless fermions on a triangular lattice, with hopping parameter t, nearest-neighbor repulsion V, and a sublattice dependent chemical potential mu s. The phase transition is found to be first order for mu s = 0, but becomes continuous with increasing mu s. The particle and hole excitation spectra exhibit dramatic changes in the vicinity of the phase transitions and in the charge density wave ordered phase. We discuss the relevance of this study to the pinball Fermi liquid phase postulated theoretically in earlier studies as well as to various strongly correlated triangular lattice materials.