The conductance behavior of the stretching processes in the STM break junction experiments was studied taking account of the effects of the energetic stability of the junction composed of benzene-dithiolate (BDT) and two Au(111) surfaces using the first principles calculations. The expected value of conductance computed with the three kinds of processes, including the one where only one junction is extended with tilted BDT, shows a flat plateau of conductance similar to the one observed by Xiao et al. [X. Xaio, B. Xu, N.J. Tao, Nano Lett. 4 (2003) 267] just before the break of the junctions. (c) 2006 Elsevier B.V. All rights reserved.