Calculations on the 3 × 3 charge density wave state in a 2H layer compound

Abstract

The authors present detailed calculations of the bandstructure, density of states and total bandstructure energy of a 2H layer compound in the 3 × 3 charge density wave (CDW) state. The calculations are performed for a variety of amplitudes and phases revealing the size and form of the energy lowering in the CDW and also the effect of the phase. It is found that a phase of -1/4 pi +2/3n pi gives the largest gain and that cluster formation is not energetically favoured. The energy gain can be fitted to a BCS form of Ax2lnn(x/c) but the parameters required are unrealistic, indicating that the energy gain is not of a simple BCS form.