Discommensurations in the commensurate charge-density-wave states of the2H-TaSe2structure

In the orthorhombic commensurate phase of $2H$-Ta${\mathrm{Se}}_2$, for certain orientations of discommensurations relative to the orthorhombic axes, discommensurations in neighboring layers may, or may not, be closely bound together, depending on the interlayer interactions; recent experimental results suggest the latter. Models for a charge-density-wave dislocation, a striped phase, and a double-honeycomb phase are suggested for the latter case. Binding of discommensurations in the hexagonal commensurate structure is also discussed.