The operation of a single molecule as a molecular nanomachine requires controlling the interaction between the molecule and its surrounding with an atomic scale precision.
Recentlty, it has been demonstrated that a single biphenyl molecule adsorbed on a Si(001) surface behaves as bistable molecule at low temperature [1].
By means of Density Functional Theory calculations, we study the underlying physics of this system. A variety of configurations for the adsorbed biphenyl molecule have been investigated [2]. We show that, during its adsorption on Si(001), one hydrogen atom dissociates from one phenyl and bonds to a neighboing surface silicon atom. After desorbing this hydrogen with a STM tip, the dynamics of the adsorbed biphenyl molecule is strongly modified: it becomes a multistable molecule having four stable states. Local density of states calculations have been performed of this configuration and compared to the experimental STM topographies. A good agreement has been observed, allowing a deeper understanding of this system [3, 4].
Our study emphasizes that, by means of a single atom manipulation, one expect to be able to control the intrinsic performance of a molecular device.
[1] M. Lastapis, M. Martin, D. Riedel, L. Hellner, G. Comtet, G. Dujardin, Science, 308 (2005) 1000.
[2] M. Mamatkulov, L. Stauffer, C. Minot and Ph. Sonnet, Phys. Rev. B 73 (2006) 035321.
[3] M. Martin, M. Lastapis, D. Riedel, G. Dujardin, M. Mamatkulov, L. Stauffer and Ph. Sonnet, Phys. Rev. Lett. 97 (2006) 216103.
[4] M. Cranney, G. Comtet, G. Dujardin, J.W. Kim, T. U. Kampen, K. Horn, Mamatkulov, L. Stauffer and Ph. Sonnet, Phys. Rev. B (submitted)
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