Sp carbon chains (spCCs) have attracted broad interest, thanks to their electronic, optical and magnetic properties, and they are considered as promising structures for nanoelectronic applications [e.g. 1]. They are also relevant for astrophysics, since their presence in interstellar clouds has been inferred from the analysis of diffuse interstellar absorption bands .
Previous works from our group have addressed the structural, mechanical, electronic and magnetic properties of spCCs, mainly by ab initio density functional theory calculations, in some cases combined with experimental measurements [3-6].
Bare spCCs are extremely unstable and reactive: this feature has driven the investigation of possible ways to enhance their stability, e.g. by binding their reactive terminations to chemical groups or to carbon nanostructures.
The Si(001) surface, organically functionalized by the adsorption of uracil-like pyrimidinic nucleobases in a “dimer bridge” configuration, may potentially constitute an interesting candidate as scaffold for supporting and stabilizing sp carbon chains. Nucleobase adsorption on Si(001) in the mentioned configuration yields indeed a well-ordered structure, with rows of adsorbed molecules overlaying silicon dimer rows, as studied by some of us .
In this work we aim at investigating the systems obtained by suspending carbon chains across nucleobase-covered silicon(001), in order to characterize the possible stabilizing effect of the Si(001):molecule scaffold on spCCs, and to explore the electronic and optical properties of the resulting structure.
 B. Standley et al., Nano Lett. 8, 3345 (2008).
 E. B. Jochnowitz, J. P. Maier, Annu. Rev. Phys. Chem. 59, 519 (2008).
 L. Ravagnan, N. Manini, E. Cinquanta, G. Onida, D. Sangalli, C. Motta, M. Devetta, A. Bordoni, P. Piseri, P. Milani, Phys. Rev. Lett. 102 245502 (2009).
 F. Cataldo, L. Ravagnan, E. Cinquanta, I. E. Castelli, N. Manini, G. Onida, P. Milani, J. Phys. Chem. B 114 14834 (2010).
 N. Manini, G. Onida, Phys. Rev. B 81, 127401 (2010).
 I. E. Castelli, N. Ferri, G. Onida, N. Manini, J. Phys.: Cond. Mat. 24, 104019 (2012).
 E. Molteni, G. Cappellini, G. Onida, G. Fratesi, Phys. Rev. B 95, 075437 (2017).