The manipulation of antimony dimers, Sb-2, on the silicon (001) surface by means of a scanning tunneling microscope (STM) has been experimentally investigated. Directed hopping of the Sb2 dimers due the STM tip can dominate over the thermal motion at temperatures between 300 and 500 K. Statistics on the enhanced hopping are reported and possible tip-adsorbate models are discussed focusing on a field-based interaction. The low yield of directed hopping is believed to be due to the low gradient in the interaction energy intrinsic to a field-based mechanism. Ultimate resolution and limiting factors of this manipulation technique are discussed.