arXiv subjects

Setianto

Publications and source records attributed to Setianto.

4 recordsLinked to original sources

arXiv2022

Nonlinear polarization effect of functionalized graphene quantum dots

Graphene quantum dots (GQDs) are nanoscale structures of graphene with quantum properties and edge effects that give photoluminescence properties. The effect of quantum confinement and differences in the nature of GQD structure makes its optical characteristics highly dependent on the size of the structure. This study explains a few exploratory semi empirical calculations of nonlinear polarization properties of functionalized GQD (fGQD) three dimensionally. Based on this, the calculation of the linear polarization and first hyperpolarization was performed by the finite field method, which is based on the expansion of the energy and dipole moment. As a result, the fGQD molecule dominantly has high optical nonlinear properties as indicated by the high \b{eta} values (71 to 4488 a.u.). In general, the first hyperpolarizabilities have a linear relationship with the dipole moments. It was potentially used for the second harmonic imaging microscopy (SHIM) application.

physics.comp-ph↗

arXiv2016

Optical Properties of Amorphous Silicon Quantum Dots(a-Si QDs) with various dot size using Extended H\"uckel Theory

A high quality amorphous silicon (a-Si) nanostructures has grown experimentally to study the origin of light emission and the quantum confinement effect in a-Si. The quantum confinement effect increases the band gap of material as the size of quantum structure decreases, which results in a blue shift in optical luminescence and energy absorption. Here we demonstrate this effect using extended H\"uckel method to calculate fundamental band gap and optical absorption energy of a-Si samples with various dot sizes. As result, when the dot size was decreased from 2.2 to 1.0 nm, the absorption spectra peak shifted toward higher energy from 2.278 eV to 3.856 eV.

cond-mat.mtrl-sci↗

arXiv2015

Effect of Anchoring Groups on the Conduction Properties of Phenyl Based on Organic Molecules Connected to Copper Leads

We report equilibrium and non-equilibrium conductance of terphenyl molecules with different anchoring groups including sulfur and nitrogen atom. The corresponding molecules are terphenyl-dithiols(TPDT) and diamino-terphenyl(DATP). The non-equilibrium Green's function (NEGF) technique has been implemented on the density functional tight-binding (DFTB) code to perform computations of the electronic transport properties of molecular devices. The NEGFs are used to compute the electronic density self-consistently with open boundary condition naturally encountered in transport problem which is imposed by the potentials at the contacts. As result, the value of the molecular conductance with amine groups is higher about ten times than the thiol anchored group

cond-mat.mtrl-sci↗

arXiv2015

Transport properties of n-phenyldithiols system anchored on Cu[111] metallic contacts

Conjugated molecules are materials which are widely studied and developed for molecular electronic technologies focusing on single molecule devices. In this paper we observed the molecular conductance of single molecule based on n phenyl ring systems with linker thiol (Sulfur) anchored on Cu[111] contacts. The non equilibrium Greens function (NEGF) implemented in density functional tight binding (gDFTB) is used to investigate the transport properties. Our result showed that, increase of the phenyl ring will decrease the HOMO LUMO energy gap. However, the conductance is decrease. The energy level of the molecule (isolated molecule) broadens and shifts after anchoring to the Cu[111] contacts.

cond-mat.mtrl-sci↗