Ab initiostudy of the structural, electronic and optical properties of ultrathin bismuth nanowires

Abstract

The energetics, structural, electronic and optical absorption properties of the bismuth nanowires Bin with n = 1, 6 have been investigated using density functional theory (DFT) in the local density approximation (LDA) including the spin–orbit coupling (SOI). The inclusion of the SOI appreciably affects all the physical properties of the wires. The stable structures form four groups: the planar structures, the caged configurations, the pyramidal structures and the helical configurations. This finding may be a guide for the construction of atomic configurations of the nanowires possessing a larger number of atoms per unit cell. The most stable wire configurations are the 5-Bi pentagonal, and the 6-Bi hexagonal and 6-Bi triple zigzag wires, which should be seen in the experiments. All the wires are metallic. The behaviour of the electron states of the second category structures is quite near to that of a linear chain where the parabolic bands cross the EF, and the number of the channels available for the electric conduction is large. Thus, one should grow the wire structures falling into the second category for achieving high conduction. For the 5-Bi pentagonal and 6-Bi hexagonal cross-sectional wires, the number of channels available for the electric conduction are ten and twelve, respectively. The SOI drastically affects the calculated optical absorption, especially in the low energy region. The absorption peaks are different in terms of the number and the energy locations for the different wires, and may be used for the characterization of the structure of a wire. Our analysis of the calculated electronic structure and the optical data of all the studied structures supports the occurrence of the 4-Bi double and/or 6-Bi triple zigzag chains in the samples of Romanov.

Structural, electronic and optical properties of ultrathin thallium nanowires – anab initiostudy

“…He proposed the presence of double zigzag chains of Bi, a suggestion that has been verified theoretically [6] by the present authors. Romanov [5] did not suggest structures for the Tl nanowires.…”

“…In Bi, we have shown [6] that all three wires, namely linear, zigzag and double zigzag chains, are stable. Further, our calculated Bi-Bi bond length of 4.03 Å is larger than the value of 2.91 Å reported by Schmidt and Springborg [12].…”

“…In earlier publications, we have investigated the most stable wire structures in Bi [6] and Pb [20] and obtained an energy minimum in each case. These results are in sharp disagreement with the observations of Schmidt and Springborg [12] who found only the linear Pb and Bi chains and the double zigzag Pb chain were stable.…”

“…Romanov [5] did not suggest structures for the Tl nanowires. One of the main aims of the present study is to establish the atomic configurations in the Tl wires prepared by Romanov. There is a considerable amount of literature on theoretical investigations of metallic wires [6][7][8][9][10][11][12][13] and it is not possible to refer to all of it here. Schmidt and Springborg [12] performed an ab-initio study of the structural and electronic properties of a few metallic chains, including Tl chains, using a full-potential linear muffin-tin orbital (FP-LMTO) method.…”

Ultrathin Nanowires—A Materials Chemistry Perspective

“…[16] Nevertheless, what really inspires a large number of scientists is the possibility of synthesizing, stabilizing, and isolating large numbers of ultrathin nanowires with the unprecedented structures predicted by theory. [17] Most of the work has been performed on metallic nanowires, from elements such as Al, [17] Pb, [17,18] Bi, [19] Si, [20][21][22] Rh, [23] Ag, [24] Cu, [25,26] and Au. [27,28] In the case of Al, Pb, Au, Cu, Rh, and Bi, wires below a certain size have been found to preferentially adopt a multiwalled architecture.…”