Regensburg 2013 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 16: Theory: Metal-insulator transitions / Electronic structure calculations

HL 16.9: Talk

Monday, March 11, 2013, 17:45–18:00, H13

Density Functional Theory Investigation of inner-Surface Methylated Aluminosilicate Nanotubes — •Joshua Elliott — University of Liverpool, Liverpool United Kingdom

We present a linear-scaling Density Functional Theory (LS-DFT) investigation into the electronic structure and stability of organic/inorganic hybrid Methyl-Aluminosilicate nanotubes (me-AlSi) as prepared and characterized in [1]. Due to the size of the considered systems (with unit-cells in excess of 350 atoms), we make use of the LS-DFT code ONETEP [2]. Following investigation of the convergence of the results with respect to the ONETEP simulation setup (kinetic energy cutoff, number and radius of the in situ optimised basis-set [2]), the effect of inner methyl incorporation on the structure of aluminosilicate nanotubes has been studied. We find that the lowest-energy tube structure has 13 unit repeat units in its circumference and a periodicity along tube axis in good agreement with available experimental data (8.0 Å[1]). We find that the presence of methyl groups does not inhibit the real space localisation of the Conduction Band (CB) and Valence Band (VB) on different sides of the nanotube cavity, nor the accumulation of positive (negative) charge at the outer (inner) surface of the tube, typical of Aluminosilicate (AlSi) nanotubes [3]. The methyl-induced shift on the me-AlSi VB and CB edges is finally quantified and suggested as an effective strategy towards doping of aluminosilicate interfaces.

[1] Phys. Chem. Chem. Phys., 13, 2, 744, (2010). [2] J. Chem. Phys. 122, 084119 (2005). [3] J. Phys.: Cond. Mat., 21, 195301 (2009).