We perform a systematic examination on the dependence of the calculated nuclear magnetic shielding constants on the chosen geometry for a selective set of density functional methods of B3LYP, PBE0, and OPBE. We find that the OPBE exchange-correlation functional performs remarkably well when either the optimized geometries or the experimental geometries are used. The popular B3LYP and PBE0 funct...

The THz transmission spectra of three trichloroanisole (TCA) compounds (2,3,4-TCA, 2,4,6-TCA and 2,5,6TCA) are measured using terahertz time-domain spectroscopy (THz-TDS). The spectrum of 2,4,6-TCA in the solid phase displays several discrete absorption peaks over frequency range from 0.1 to 1.5 THz, with significant peaks observed at 0.6, 0.95 and 1.2 THz. A weak absorption peak is observed ne...

Certain organic compounds posess the ability to change color under the influence of light, called photochromism. This change is often due to ultrafast chemical transition from open to closed ring isomers (photocyclization). Information thechnology applications of these photochromics require the reverse transformation to be very slow in the dark. We have applied Density Functional Theory (DFT) m...

Afinidades eletrônicas de doze moléculas pequenas foram calculadas pela teoria de funcional de densidade empregando dois funcionais diferentes(B88-P86 e B3LYP) combinados com três conjuntos de bases diferentes(6-31++G**, 6-311++G** e aug-cc-pVTZ). O método de função de Green para camada na valência exterior também foi empregado para os cálculos de afinidades eletrônicas das moléculas. Duas melh...

We investigate the zinc vacancy effects on the electronic structures and magnetic properties of Sc-doped ZnO, by performing first-principles calculations within both GGA + U and Heyd–Scuseria–Ernzerhof hybrid functional methods. We find that Sc impurities stabilize considerably Zn vacancies. The electronic and magnetic analysis shows a half metallic ferromagnetic character with a total magnetic...

adsorption of no2 molecule on pristine and n-doped tio2 anatase nanoparticles have been studied using the density functional theory (dft) technique. the structural properties (such as bond lengths and bond angles) and the electronic properties (such as density of states, band structures and atomic partial charges) have been computed for considered nanoparticles. the results show that, the adsor...

the storage capacity of hydrogen on na-decorated born nitride nanotubes (bnnts) is investigated by using density functional theory within quantum espresso and gaussian 09. the results obtained predict that a single na atom tends to occupy above the central region of the hexagonal rings in (5,0) and (3,3) bnnt structures with a binding energy of -2.67 and -4.28 ev/na-atom respectively. when a si...

we have investigated structure and electronic properties of au and si liner chains using the firstprinciplesplane wave pseudopotential method. the transport properties and conductance of these twoliner chains are studied using landauer approaches based on density functional theory (dft). weobtain density of states and band gap using kohn-sham and wannier functions as well as quantumconductivity...

To investigate the electromagnetic interaction of molecules inside the nanotubes, first, the structure of nanotubes B16N16 was optimized with hybrid density functional theory (B3LYP) using the EPR-II basis set, then Cu, Cu+, Cu++ were located in nanotube and we studied the total energy, band gap energy, electrical potential, changes of band gap energy in terms of total energy and dipole moment ...

graphyne and graphdiyne families of flat carbon (sp2/sp) networks with high degrees of π-conjunction are attracting much attention due to their promising electronic, optical, and mechanical properties. in the present investigation we have studied the structural, mechanical, electrical and optical properties of halogenated graphdiyne and graphyne. the optical spectra of pure and halogenated stru...