Strain engineered graphene using a nanostructured substrate: I Deformations

Using atomistic simulations we investigate the morphological properties of graphene deposited on top of a nanostructured substrate. Sinusoidally corrugated surfaces, steps, elongated trenches, one dimensional and cubic barriers, spherical bubbles, Gaussian bump and Gaussian depression are considered as support structures for graphene. The graphene-substrate interaction is governed by van der Waals forces and the profile of the graphene layer is determined by minimizing the energy using molecular dynamics simulations. Based on the obtained optimum configurations, we found that: (i) for graphene placed over sinusoidally corrugated substrates with corrugation wave lengths longer than 2\,nm, the graphene sheet follows the substrate pattern while for supported graphene it is always suspended across the peaks of the substrate, (ii) the conformation of graphene to the substrate topography is enhanced when increasing the energy parameter in the van der Waals model, (iii) the adhesion of graphene into the trenches depends on the width of the trench and on graphene's orientation, i.e. in contrast to a small width (3 nm) nanoribbon with armchair edges, the one with zig-zag edges follows the substrate profile, (iv) atomic scale graphene follows a Gaussian bump substrate but not the substrate with a Gaussian depression, and (v) the adhesion energy due to van der Waals interaction varies in the range [0.1-0.4] J/m^2.Comment: 12 pages and 16 figures, To appear in Phys. Rev.

Computational molecular characterization of the flavonoid rutin

In this work, we make use of a model chemistry within Density Functional Theory (DFT) recently presented, which is called M05-2X, to calculate the molecular structure of the flavonoid Rutin, as well as to predict the infrared (IR) and ultraviolet (UV-Vis) spectra, the dipole moment and polarizability, the free energy of solvation in different solvents as an indication of solubility, the HOMO and LUMO orbitals, and the chemical reactivity parameters that arise from Conceptual DFT. The calculated values are compared with the available experimental data for this molecule as a means of validation of the used model chemistry

Interaction of nitrite with alkali oxides

The structural and electronic properties of nitrite (ONO) and alkali oxides (OX; X = H, Li, Na, K) have been investigated theoretically by performing ab initio calculations in the HF level. These species form alkali-metal nitrates (ONOOX). The optimized structures and the electronic properties of the systems ONO, OX, and ONOOX are obtained

Theoretical investigation of melatonin and its hydroxy isomers

The structural and electronic properties of melatonin and its six hydroxy isomers have been investigated theoretically by performing semi-empirical and ab initio molecular orbital theory calculations. The geometry of the systems has been optimized considering the semi-empirical molecular orbital theory at the level of AM I, and the electronic properties of the systems have been calculated by ab initio RHF including full MP2 correlation correction in their ground state. Conclusions were drawn by comparing with experimental results

Theoretical investigation of quercetin and its radical isomers

The structural and electronic properties of quercetin and its five radical isomers have been investigated theoretically by performing semi-empirical molecular orbital theory calculations. The geometry of the systems have been optimized and the electronic properties of the systems considered have been calculated by semi-empirical self-consistend-field molecular orbital theory at the level AM1 within UHF formalism in their ground state. Conclusions have been drawn by comparing with experimental results

Structural and electronic properties of 'benzorods'

The structural and electronic properties of benzorods, carbon nanorods made of benzen molecules, have been investigated systematically by performing semi-empirical self-consistent-field molecular-orbital theory calculations at AM1-RUF level. The benzorod represented by nC6 contains n benzonoid rings placed parallel to each other forms a stable structure

Structural and electronic properties of porphyrin skeleton of chlorophyll

The structural and electronic properties of porphyrin skeleton of chlorophyll have been investigated theoretically by performing semi-empirical and ab-initio molecular orbital theory calculations. The geometry of the system has been optimized considering the semi-empirical molecular orbital theory at the level of PM3, and the electronic properties of the system have been calculated by ab-initio restricted Hartree-Fock (RHF) with full MP2 correlation correction in the ground state included

Structural and electronic properties of guanine and guanosine

The structural and electronic properties of guanine and guanosine have been investigated theoretically by performing semi-empirical and ab initio molecular orbital theory calculations. The geometry of the systems have been optimized considering the semi-empirical molecular orbital theory at the level of Austin model 1, and the electronic properties of the systems have been calculated by ab initio restricted Hartree-Fock with including full MP2 correlation correction in their ground state

Titanium coverage on a single-wall carbon nanotube: molecular dynamics simulations

The minimum energy structures of Ti covered (8,0) single-wall carbon nanotube (SWNT) have been investigated theoretically. Using available experimental data and the results of density functional theory calculations, we first parametrized a reliable empirical many-body potential energy function (PEF) for the CTi binary system. The PEF used in the calculations includes two- and three-body atomic interactions. Then performing molecular dynamics simulations at 1 and 300 K, we obtained the minimum-energy configurations for Ti covered (8,0)-SWNT. The configurations reported here include low and high coverage of Ti on nanotubes. We have found that one layer of Ti did not distort the nanotube significantly, whereas two-layer coverage showed an interesting feature: the second layer of Ti pushed the first layer inside the wall of nanotube, but the general shape of the nanotube was not affected so much