Surface states and second harmonic generation at the (1 1 0) nickel surface from a first-principles calculation

The electronic and magnetic structure of the ferromagnetic (1 1 0) nickel surface is calculated within the first-principles Layer Korringa Kohn Rostocker (LKKR) method. Spin-dependent results are given for the local density of states which show the existence of several empty surface states at the high symmetry directions of the surface Brillouin zone. Unoccupied surface states with their dispersion are described in detail and compared with inverse photoemission measurements. Second harmonic generation can be calculated in magnetic systems within the framework of the LKKR method. We present preliminary results which show that surface states are responsible for an enhancement of the second harmonic electric current in the vicinity of the (1 1 0) nickel surface. Such a surface state contribution to the second harmonic signal has recently been observed in Ni(1 1 0).