[...]... carried out The full-electron 6-31G(d) basis set uses four s-type, nine P-type, and six d-type Gaussian functions to represent the electrons of a and Si atom The total DOS and the s, p, and d projections obtained using that basis set are shown in Figure 3 The states around the Fermi level have mostly a p-character and a bandgap of 0.72 eV; the midgap is at −2 22 eV The LANL2DZ basis set supports elements... −5 83 eV using the B3PW91 functional with the LANL2DZ basis set and ECP 8 Luis A Agapito and Jorge M Seminario DOS (states eV–1 atom–1) 3.5 s p d(t2g) 3 d(eg) 2.5 total 2 1.5 1 0.5 0 –15 –10 –5 0 5 Energy (eV) Figure 2 DOS for the Pd crystal obtained using the B3PW91 functional and LANL2DZ basis set and ECP The Fermi level is at −5 59 eV and 1 1 A3 = aˆ + aˆ x y 2 2 The calculation of the electronic... coefficients, cri , of the molecular orbitals are found by solving iteratively Eq (11) [25] n = KS 2 i (15) i=1 At all steps of the iteration, the expansion coefficients are updated Consequently, new KS molecular orbitals, Eq (10), and electron densities, Eq (15), are obtained during the iterative process When self-consistency is reached, the ground-state electron density and KS molecular orbitals can... Single-walled carbon nanotubes SWCNTs are one-dimensional crystals with interesting mechanical and electrical properties (See for instance [27]) The geometry and 0.9 s DOS (states eV–1 atom–1) 0.8 0.7 p d total 0.6 0.5 0.4 0.3 0.2 0.1 0 –15 –10 –5 0 5 10 Energy (eV) Figure 3 DOS for a silicon crystal calculated using the B3PW91 method and the 6-31G(d) basis set 10 Luis A Agapito and Jorge M Seminario... applied to the junction in order to account for the reorganization of the molecular electronic structure due to the presence of such field This allows us to study among others the effects of the external bias potential on charge transfer between the molecule and the contacts, the shift of molecular levels and the shape changes of the molecular orbitals, which have a direct effect on the conductance of the... low-current region of (A) The coplanar conformation of the molecular junction is shown in the lower part of (B) The C, H, S, N, O, and Au atoms are colored grey, white, yellow, blue, red, and green, respectively first charge state (anion), and the perpendicular conformational state are calculated for this Au6 –nitroOPE–S–Au1 junction Also, two different and possible geometrical conformations are calculated... junctions considered in this work, the transport of electrons is described by the Landauer formalism A DFT-GF implementation of the Landauer formalism is used to calculate the I–V of metal–nitroOPE–metal junctions in different conformational and charge states Gold and the (4, 4) CNT are tested as metallic contacts, and in both cases the metal–nitroOPE–metal junction presents high conductance when the... interfaces is schematized in Figure 12 Zones I and V correspond to the regions of the junction where both contacts (contact 1 and contact 2) behave as bulk materials and their effect on the junction is accounted using the Green function method The critical part of the junction is the region where both bulk materials are in direct contact; the formation and breakage of molecular bonds takes place in this region,... 3047.52490 457.369510 103.948690 29.2101550 9.28666300 3.16392700 u where i and j count over all electrons and b counts over all nuclei, and Zb is the atomic number of the atom b If the system contains n electrons then the wavefunction of the molecular system is a function of 3n spatial coordinates and n spin coordinates Therefore, calculating the complete electronic wavefunction is computationally challenging... the contacts is obtained from molecular calculations (HiM and HMi shown in Eq (30)) that consider the atomistic nature of the contact– molecule interface The interaction terms defined in Eq (31) are added to the molecular Hamiltonian to account for the effect of the contact on the molecule: ⎞ ⎛ H1M H12 H11 ⎟ ⎜ (34) He = ⎝ HM1 HMM + 1 + 2 HM2 ⎠ H21 H2M H22 14 Luis A Agapito and Jorge M Seminario To account . h0" alt="" ⑦ 17 THEORETICAL AND COMPUTATIONAL CHEMISTRY Molecular and Nano Electronics THEORETICAL AND COMPUTATIONAL CHEMISTRY SERIES EDITORS Professor P. Politzer Department of Chemistry University. (Editor) VOLUME 16 Computational Photochemistry M. Olivucci (Editor) VOLUME 17 Molecular and Nano Electronics: Analysis, Design and Simulation J.M. Seminario (Editor) VOLUME 18 Nanomaterials: Design and Simulation P. B and Simulation P. B. Balbuena and J.M. Seminario (Editors) ⑦ 17 THEORETICAL AND COMPUTATIONAL CHEMISTRY Molecular and Nano Electronics: Analysis, Design and Simulation Edited by J. M. Seminario Department