First principles study on the structure and STM image of acetylene adsorption on Ge(0Â 0Â 1)

► For the first time the bias-dependent STM image of C2H2/Ge(0 0 1) are studied. ► The observed two features are di-σ and paired-end-bridge configuration. ► Atomic and electronic structure explains the bias dependence for Feature B. ► Tip-sample interaction is the major cause for the depression in Feature A.