Alkali metals adsorbed on Ge(0 0 1)-p(1 x 2) exhibit a variety of atomic arrangements depending on the coverage. We present theoretical investigation of a quasi-isolated alkali atom adsorption on the Ge(0 0 1)-p(1 x 2) surface, with and without a missing-dimer defect. Stable adsorption sites are found and the corresponding adsorption energies are compared. For completeness, STM images are simulated for the energetically most favourable atomic configurations. (C) 2010 Elsevier B. V. All rights reserved.