# Green's function calculation of Ballistic Electron Emission Microscopy currents (BEEM v2.1)

## Description

Abstract We describe the FORTRAN-90 program BEEM v2.1 for the computation of real and reciprocal space currents in Ballistic Electron Emission Microscopy (BEEM), and Spectroscopy (BEES). Based on a LCAO Hamiltonian, the equilibrium one-particle Green's functions of a semi-infinite crystal are obtained using a decimation technique. By means of Keldysh's formalism, the STM tip is coupled to this crystal, and expressions for BEEM currents in real and reciprocal space are obtained. Finally, a Dyson-like e... Title of program: BEEM Catalogue Id: ADLR_v1_0 Nature of problem We describe the Fortran-90 program BEEM v2.1 for the computation of real and reciprocal space currents in Ballistic Electron Emission Microscopy (BEEM), and Spectroscopy (BEES) [1-4]. Versions of this program held in the CPC repository in Mendeley Data ADLR_v1_0; BEEM; 10.1016/S0010-4655(99)00502-0 This program has been imported from the CPC Program Library held at Queen's University Belfast (1969-2019)