Relaxation of Al(001) and Al(110): Surface embedded Green function total-energy and force calculation

Surface total energy and force calculations have been performed for the Al(001) and A1(110) surfaces using the surface embedded Green function method. The force on each surface layer has been calculated in two ways: from a direct expression, and from the slope of the total energy versus the interlayer separation curve. Excellent agreement has been obtained between the two methods. For the Al(001) surface, the calculated surface relaxation was -1+/-2 %, which is in excellent agreement with experiment. For the Al(110) surface, the calculated surface relaxation of -11 % is in good agreement with experiment. Errors associated with various approximations used in calculating the total energy, force, work function, and surface relaxation have also been evaluated.