Symmetry analysis of the triply commensurate charge-density wave states in the 2H-TaSe₂structure

Standard group theoretical analysis of phase transitions from the hexagonal parent phase of the 2H-TaSe 2 structure into triply commensurate phases is performed. Possible space-group symmetries and the number of single-domain states are determined. A two-layer model of the 2H-TaSe 2 structure is analysed and the authors show how two-layer states correspond to single-domain states of triply commensurate phases of various space-group symmetries. Orthorhombic distortions of hexagonal single-layer states are briefly discussed.