O(N) TIGHT-BINDING METHODS WITH FINITE ELECTRONIC TEMPERATURE

The application to tight-binding O(N) methods of the approximation of Gillan [J. Phys. Condens. Matter 1, 689 (1989)] for estimating the ban d energy of a metal at an electron temperature of zero kelvin from the band free energy for electrons with a finite temperature is presented . The inclusion of the finite electron temperature improves convergenc e of the methods. Provided it is less than about 10% of the bandwidth, the error in the estimated energy compared with the true T=0 value is found to be less than 5% for titanium. The method is also found to gi ve useful estimates of the zero-temperature band energy for silicon, d iamond, and graphite. The calculated forces are tested on a molybdenum cluster.