Dehydrogenation of Benzene under an electric current

M. R. RELAÑO; P. ABUFAGER; S. DÍAZ-TENDERO; M. ALCAMÍ; F. MARTÍN ; N. LORENTE

Zaragosa

Workshop; Electron Dynamics on Surfaces and Nanostructures; 2014

In the latest years there has been an increasing interest on forcing chemical reactions by using a Scanning Tunnelling Microscope (STM) [1, 2]. The tunnelling electrons created by the microscope can induce vibrational or electronic excitations, achieving different phenomena of the adsorbates placed at the surface. Thus, the STM is a way to control chemical reactions on the nano scale. Of course, STM not only can induce chemical reactions, but it also provides us with real-space images of molecules adsorbed on surfaces, giving us the chance of determining adsorption sites and space orientation of the molecules. We present here the study of a single benzene molecule, placed in between two Cu(100) leads. Through this copper leads, a finite potential will be created, affecting thus, the structure of the C6H6 molecule, i.e. forcing its dehydrogenation. We show how this phenomenon can be analyzed through the change in the atomic forces experienced by each pair of C-H atoms. Moreover, the electronic structure of the organic molecule will be modified as the current in between the two Cu leads is increased. Our transport calculations will involve a simple Siesta calculation of the electrodes and a TranSiesta one of the scattering region. TranSiesta [3] is a method to solve the electronic structure of a finite open system, which has been placed in between two semi-infinite metallic sheets. A finite potential is then applied between the two sheets, giving rise to an electric current. TranSiesta solves the electronic density from the DFT Hamiltonian using techniques based on the Green?s function, instead of the commonly used diagonalization method. Therefore, before performing a TranSiesta calculation, one must perform a Siesta one, where those Green?s Function are calculated, as well as the charge density of the open system [4]. References [1] P. Avouris, Acc.Chem. Res. 18, 95 (1995) [2] W. Ho,Acc. Chem. Res. 31,567 (1998) [3]http://departments.icmab.es/leem/siesta/Documentation/Manuals/siesta-3.1-manual/node89.html [4] M.Brandbyge et al., Phys. Rev. B 65, 165401 (2002)