Navegando por Assunto "Semi-empirical"

Agora exibindo 1 - 2 de 2

Acesso aberto (Open Access)
Propriedades elétricas de nanoantena de grafeno
(Universidade Federal do Pará, 2015-02-24) TAVARES, Simone Cristina da Costa; DEL NERO, Jordan; http://lattes.cnpq.br/5168545718455899
The incessant rush for discovering new materials and the search for new solutions to the tech-nological problems and equipment that have devices with better performance than the currently available, operating at ever smaller scales led us to study antennas that allow to occupy an increasingly small space. This permitted us to show the study of the electronic carbon nanotube structure and the electrical properties of graphenenano-antenna as its precursors. The develop-ment of antennas made of carbon nanotube and graphene is, in the moment, a technological possibility opened to state of art. In this paper we investigate the electronic transport for gra-phene organic material using it as a nano-antenna where we present simulations of quantum calculations derived from Hartree-Fock theory and semi-empirical method, which is given by the electron charge distribution along the structure. The structural parameters of the optimized structure have been fully calculated, including external electric field across the matrix layer of closed Roothaan-Hall model. Featuring a characteristic related to the electrical response which results a transistor device field effect, with capacitance and operating frequency in 90 THz un-der an operating voltage around the 0,82 V rectification and we show, also, the Fowler-Nord-heim model and Millikan -Lauritsen for graphene structure.
Acesso aberto (Open Access)
Transporte eletrônico de nanofita de grafeno sob a influência de constrições e oxidação
(Universidade Federal do Pará, 2014-11-14) SOUSA, Mario Edson Santos de; REIS, Marcos Allan Leite dos; http://lattes.cnpq.br/8252507933374637; DEL NERO, Jordan; http://lattes.cnpq.br/5168545718455899
In this work we investigate the effects of oxidative functionalization groups on the structure of graphene nanoribbons and also the effects of constrictions caused by the emergence of a nanopore to the tape, where these effects were analyzed by means of electron transport via longitudinal external field center. Our calculations were parameterized by the semi-empirical model of the theory of extended Huckel-ETH, adopting the method of Green's functions of non equilíbrio- NEGF. The currents were calculated through the Landauer equation that uses the transmission function of the region spreader to the flow of electrons with energy E coming out of the electrode. By means of this approach, it was possible to analyze the behavior of charge carriers in each of the proposed devices, as well as the nature of such behavior. Were found to curves I(V) two transport regimes: Ohmic and NDR, checking maximum current and also the threshold voltage (VTh1