Journal of Molecular Graphics and Modelling 42 (2013) 115–119 Contents lists available at SciVerse ScienceDirect Journal of Molecular Graphics and Modelling journa l h om epage: www.elsevier.com/locate/JMGM Electronic properties of functionalized (5,5) beryllium oxide nanotubes Ernesto Chigo Anota a,∗ , Gregorio Hernández Cocoletzi b a Benemérita Universidad Autónoma de Puebla, Facultad de Ingeniería Química, Ciudad Universitaria, San Manuel, Puebla, Código Postal 72570, Mexico b Benemérita Universidad Autónoma de Puebla, Instituto de Física ‘Luis Rivera Terrazas’, Apartado Postal J-48, Puebla 72570, Mexico a r t i c l e i n f o Article history: Accepted 29 March 2013 Available online 6 April 2013 Keywords: Beryllium oxide nanotubes Hydroxyl Point defects Work function DFT theory a b s t r a c t Using the density functional theory (DFT) we study the structural and electronic properties of function- alized (5,5) chirality single wall beryllium oxide nanotubes (SW-BeONTs), i.e. armchair nanotubes. The nanotube surface and ends are functionalized by the hydroxyl (OH) functional group. Our calculations consider the Hamprecht–Cohen–Tozer–Handy functional in the generalized gradient approximation (HCTH-GGA) to deal with the exchange–correlation energies, and the base function with double polar- ization (DNP). The geometry optimization of both defects free and with point defects nanotubes is done applying the criterion of minimum energy. Six configurations are considered: The OH oriented toward the Be (on the surface and at the end), toward the O (on the surface and at the end) and placed at the nanotube ends. Simulation results show that the nanotube functionalization takes place at the nanotube ends with the Be O bond displaying hydrogen-like bridge bonds. Moreover the nanotube semiconductor behavior remains unchanged. The polarity is high (it shows a transition from covalent to ionic) favoring solvatation. On the other hand, the work function low value suggests this to be a good candidate for the device fabrication. When the nanotube contains surface point defects the work function is reduced which provides excellent possibilities for the use of this material in the electronic industry. © 2013 Elsevier Inc. All rights reserved. 1. Introduction Since the carbon nanotubes discovery by Iijima [1] these 1D structures have attracted the attention of the scientific community, they have been investigated both theoretically and experimentally. Similar studies have been performed on boron nitride nanotubes [2,3], zinc oxide nanotubes [4–8] and nanosheets [9,10]. However less attention has been paid to the earth alkaline compounds such as the 2D beryllium oxide (BeO) which was predicted to exist by Con- tinenza et al. [11] in 1990. BeO nanosheets display graphene-like hexagonal configuration with sp 2 hybridization. Simulation studies on the BeO nanosheets by Baumeier et al. [12] and Wu et al. [13] have demonstrated that the pristine nanosheets behave as semi- conductors however when they are fluorinated and hydrogenated [14] transform into semimetal. At the same time Baumeier et al. [12] have predicted the single wall BeO nanotubes (BeONTs) for- mation with semiconductor behavior and wide band gap in the interval of [7.3,8.8] eV for different chiralities (zig–zag and armchair structures). It is important to remark that these BeONTs display properties which are helicity independent. Studies on BeONTs [15] ∗ Corresponding author. Tel.: +52 222 2 29 55 00. E-mail addresses: ernesto.chigo@correo.buap.mx, echigoa@yahoo.es (E. Chigo Anota). doped with carbon and nitrogen considering different chiralities show energy gap reductions from 5.59 eV for pristine (6,6) BeONT, to 1.1 for BeONT:B, to 1.5 for BeONT:C and to 1.0 eV for BeONT:N. At the same time the beryllium vacancies induce an increase in the magnetic moment. As it stands doped BeONTs may be applied technologically in the spintronic industry. Therefore in this work we address the study of structural (bond lengths and nanotube diameters) and electronic properties (polarity, chemical potential and work function) of single wall (5,5) BeONTs. The nanotubes are considered in the armchair configuration and functionalized at the ends and surface by the hydroxyl group (OH). The choice of (5,5) chirality is because this structure exhibits a strain energy of 0.058 eV/atom which is low compared with other chiralities such as the (n,0). This energy value indicates that the nanostructure may easily phase transform from 2D to 1D [12]. We also analyze the point defect effects on the BeONT–OH properties by paying attention on the vacancies of Be and O. Our studies are done using molecular simulation (local properties) within the density func- tional theory in order to explore possible applications in molecular sensing or field emission devices. 2. Simulation models and methods First principles total energy calculations are performed to study (5,5) SW-BeONTs–OH structural and electronic properties. To deal 1093-3263/$ – see front matter © 2013 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.jmgm.2013.03.007