Estudo das propriedades estruturais e eletrônicas de cadeias de carbono quasi-unidimensionais

Abstract

Elemental Carbon and its different allotropes, including monoatomic carbon chains, have been attracting great attention in scientific research. In view of the importance of materials formed by carbon in both physics and chemistry, in this work we study the structural and electronic properties of quasi-one-dimensional carbon chains using ab initio calculations based on the density functional theory (DFT), the method of plane waves, Norm-Conserving pseudopotential, LDA-CA-PZ and GGA-PBE approximations. The calculations are implemented on CASTEP computacional package. We explore its optimized geometries, its electrical conductivity from the electronic structure and state density. As a by-product of our analysis, we revealed a direct energy gap of 4.185 eV and 4.043 eV for the 1A1C and 2A2C-TRANS structures, respectively, using the GGA funcional. The values found for the energy gap for these systems indicate that the studied structures show the behavior of an insulating material. The calculation of the total energy obtained for the 2A2C-CIS structure showed a higher value than the total energy calculated for the 2A2C-TRANS system, which reveals that the 2A2C-CIS conformation represents a minimum local energy while the 2A2C-TRANS conformation represents a global minimum. The band structure of the systems has energy bands with energy states well located along the paths ΓZ and XΓ. The molecular orbitals occupied with higher energy levels of the 1A1C structure show more localized states, while for the 2A2C-TRANS structure they present more scattered states.