A new photodetector structure based on graphene nanomeshes: an ab initio study

• Babak Sakkaki,
• Hassan Rasooli Saghai,
• Ghafar Darvish and
• Mehdi Khatir

Beilstein J. Nanotechnol. 2020, 11, 1036–1044, doi:10.3762/bjnano.11.88

• electronic and optical characteristics of various GNM structures. To investigate the device-level properties of GNMs, their current–voltage characteristics are explored by DFT-based tight-binding (DFTB) in combination with non-equilibrium Green’s function (NEGF) methods. Band structure analysis shows that

• voltages, we use the density-functional-based tight-binding (DFTB) method in combination with non-equilibrium Green's functions (NEGFs). As an approximate density-functional method, DFTB holds nearly the same accuracy, but at much lower computational cost, allowing for the investigation of the electronic

• and attach two electrodes to them. Then, we calculate dark current and photocurrent of each structure. The DFTB+NEGF approach is used to calculate the dark current of devices, and for the calculations of the photocurrent, we use first-order perturbation theory in the framework of the Born

New 2D graphene hybrid composites as an effective base element of optical nanodevices

• Olga E. Glukhova,
• Igor S. Nefedov,
• Alexander S. Shalin and
• Мichael М. Slepchenkov

Beilstein J. Nanotechnol. 2018, 9, 1321–1327, doi:10.3762/bjnano.9.125

• -mechanical SCC DFTB method [12][13] The 2D CNT–graphene hybrid film was modelled by two graphene monolayers between which single-walled CNTs with different diameters were regularly arranged at different distances from each other. As was shown earlier [14], the composites with zigzag tubes (n, 0) (n = 10, 12

• topological forms were previously discovered by experimental investigations [11]. The atomistic model of the composite unit cell was obtained by means of the original ”method of magnifying glass” described in detail in [14] using the SCC DFTB method. Figure 1 shows a general view of the composite fragment

The electrical conductivity of CNT/graphene composites: a new method for accelerating transmission function calculations

• Olga E. Glukhova and
• Dmitriy S. Shmygin

Beilstein J. Nanotechnol. 2018, 9, 1254–1262, doi:10.3762/bjnano.9.117

• modern computing tools. The non-equilibrium Green function (NEGF) method with density functional tight-binding (DFTB) scheme or density functional theory (DFT) scheme is used to calculate the electrical conductance of molecular structures consisting of atoms of various elements with high accuracy [8

Invariance of molecular charge transport upon changes of extended molecule size and several related issues

• Ioan Bâldea

Beilstein J. Nanotechnol. 2016, 7, 418–431, doi:10.3762/bjnano.7.37

• organic molecules. For concrete cases, the model parameters (Hμ,μ′, τL,R, tL,R) can be obtained within density-functional-based, tight binding (DFTB) frameworks [18][19][20], which represent the state-of-the-art for such larger systems. In a biased junction, they may also nontrivially depend on V and, if

• within this framework include, e.g., atomic chains, quantum wires, carbon nanotubes, and (possibly DNA-based) bio and large organic molecules. To determine the model parameter values, density functional based tight binding (DFTB) frameworks [18][19][20] represent the state-of-the-art. It is worth

Electronic and transport properties of kinked graphene

• Jesper Toft Rasmussen,
• Tue Gunst,
• Peter Bøggild,
• Antti-Pekka Jauho and
• Mads Brandbyge

Beilstein J. Nanotechnol. 2013, 4, 103–110, doi:10.3762/bjnano.4.12

• the less rigorous DFTB method [39] and obtained results in agreement with the trend in reaction-barrier reduction obtained above. We may understand the reaction barrier and its change with curvature by considering the changes in carbon bond lengths. The barrier is due to the fact that the reacting

On the reticular construction concept of covalent organic frameworks

• Binit Lukose,
• Agnieszka Kuc,
• Johannes Frenzel and
• Thomas Heine

Beilstein J. Nanotechnol. 2010, 1, 60–70, doi:10.3762/bjnano.1.8

• (DFT) and the related Density Functional based tight-binding (DFTB) method. Linear, trigonal and hexagonal building blocks have been selected for designing hexagonal COF layers. High-symmetry AA and AB stackings are considered, as well as low-symmetry serrated and inclined stackings of the layers. The

• electronic densities of states (DOS) are similar and not significantly different from that of a monolayer. The band gaps are found to be in the range of 1.7–4.0 eV. COFs built of building blocks with a greater number of aromatic rings have smaller band gaps. Keywords: covalent organic frameworks; DFTB

• 0.40 kJ•mol−1, respectively; hence supporting the endothermic nature of the condensation reaction and is in reasonable agreement with our DFTB results (Table 2). Electronic properties All COFs, including the reference structures, are semiconductors with their band gaps lying between 1.7 eV and 4.0 eV