Calculation of VLEED spectra with the extended linear augmented plane wave kp method

We describe a new method to calculate the VLEED (very low energy electron diffraction) spectra within the Bloch waves approach. The method is based on the variational solution of the Schr?dinger equation for a semi-infinite crystal. Inside the solid the trial LEED functionΦ is a linear combination of propagating and evanescent Bloch waves, which are generated by the inverse ELAPW (extended linear augmented plane waves)-kp method. The trial function is smoothly continuous over the whole space, and it satisfies by construction the equation (Ĥ − E)Φ=0 both in the crystal and in the vacuum half-spaces. In the surface layer the equation δ‖(Ĥ − E)Φ‖=0 is solved. To illustrate the properties of the method we discuss its application to the 1D case. We have performed a self-consistent band structure calculation of the 1T chalcogenide VSe₂ and obtained from the first principles the normal-incidence target current spectrum (TCS) for its (0001) surface. Presented at the VIII-th Symposium on Surface Physics, Třešt’ Castle, Czech Republic, June 28 – July 2, 1999.