Cyclo[(-beta(3)-HGly)(4)-] and its oligomers were studied using the density function B3LYP method. Their energetics and structural characteristics were calculated and analyzed. Significantly, we observed that the average interaction energy between two adjacent monomers in the beta(3)-cyclopeptide oligomers showed marked increase upon addition of more monomers. However, the enhancement will gradually become weaker and eventually reach a plateau, giving rise to a stable nanotube. The same phenomenon was observed for their geometric structures and dipole moments of the assembly. Based on these new insights, we suggest that the synergetic effect resulted from addition of monomers will facilitate the enhancement of favorable interaction of the nanotube, which is the primary driving force of self-assembly. (C) 2003 Elsevier Science B.V. All rights reserved.