Eur. Phys. J. B (2016) 89: 98
https://doi.org/10.1140/epjb/e2016-70011-1

Regular Article

Electronic structure of uracil-like nucleobases adsorbed on Si(001): uracil, thymine and 5-fluorouracil^*

¹ European Theoretical Spectroscopy Facility (ETSF) and Department of Physics, Università degli Studi di Milano, via Celoria 16, 20133 Milano, Italy
² Department of Physics, Università degli Studi di Cagliari, Cittadella Universitaria di Monserrato, S.P. Monserrato-Sestu Km. 0.700, 09042 Monserrato ( CA), Italy
³ CNR-IOM SLACS Cagliari c/o Department of Physics, Università degli Studi di Cagliari, Cittadella Universitaria di Monserrato, S.P. Monserrato-Sestu Km. 0.700, 09042 Monserrato ( CA), Italy

^a e-mail: elenamltn@gmail.com

Received: 7 January 2016
Received in final form: 22 February 2016
Published online: 13 April 2016

Abstract

We study the electronic properties of the Si(001):Uracil, Si(001):Thymine, and Si(001):5-Fluorouracil systems, focusing on the Si dimer-bridging configuration with adsorption governed by carbonyl groups. While the overall structural and electronic properties are similar, with small differences due to chemical substitutions, much larger effects on the surface band dispersion and bandgap show up as a function of the molecular orientation with respect to the surface. An off-normal orientation of the molecular planes is favored, showing larger bandgap and lower total energy than the upright position. We also analyze the localization of gap-edge occupied and unoccupied surface states.