Abstract: In uniform external electric field, CO molecules adsorbed on the surface of nonocones that grow on a transition metal substrate are modeled as equivalent dipoles.Mathematical models are given with consideration of three interactions,i.e.,interaction between dipoles and local electric field,dispersion interaction between dipoles and dipoles,as well as interaction between dipoles and atoms of nanocone surface.Spatial distribution of CO molecules adsorbed on nanocone surfaces is obtained by Monte-Carlo method.It shows that the CO molecules adsorbed on nanocone surfaces agglomerate locally with these interactions,and molecules adsorbed on top of the nanocone become dense with a decrease of conical angle of nanocone.It results in more powerful interaction among molecules.It may provide an explanation for abnormal infrared effects(AIREs) observed as CO molecules adsorbed on nanostructured transition metal surfaces.

Key words: nanocone, adsorbed molecules, local electric field, Monte Carlo method