Structure of aluminum atomic chains

Sen, Prasenjit; Çiraci, S.; Buldum, Alper; Batra, Inder P.

doi:10.1103/physrevb.64.195420

Cited by 72 publications

(101 citation statements)

References 38 publications

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“…These angles decrease almost linearly as the chains are stretched, and become approximately zero for d z larger than 2.5Å. Interestingly, if the distance is reduced below the zigzag minimum the system falls into another stable configuration with a ladder arrangement, similar to that predicted by Sen et al [16]. Fig.…”

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Conductance Oscillations in Zigzag Platinum Chains

et al. 2005

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Using first principles simulations we perform a detailed study of the structural, electronic and transport properties of monoatomic platinum chains, sandwiched between platinum electrodes. First, we demonstrate that the most stable atomic configuration corresponds to a zigzag arrangement that gradually straightens as the chains are stretched. Secondly, we find that the averaged conductance shows slight parity oscillations with the number n of atoms in the chain. Additionally, the conductance of chains of fixed n oscillates as the end atoms are pulled apart, due to the gradual closing and opening of conductance channels as the chain straightens. 73.40.Jn,71.15.Ap The existence of single atom chains was demonstrated some time ago using the scanning tunneling microscope (STM) and mechanically-controllable break junctions (MCBJ) [1] where a quantized conductance close to G 0 = 2 e 2 /h for gold was measured, in agreement with previous theoretical predictions [2]. Since then, a number of experiments [3,4] and theoretical calculations [5] have proved that the 5d elements Au, Ir and Pt can be used to produce monoatomic chains. For gold chains [1], the average distance between conductance peaks was found to be 2.5Å with the conductance G of the last plateau being very close to G 0 . The ensemble-averaged conductance also shows small oscillations around G 0 as the length of the chain increases [4].For platinum, the average distance between the peaks in the length-histograms is about 1.9-2.3Å [3,4]. In contrast with gold, the conductance is no longer an integer multiple of G 0 , but instead decreases from 1.6 G 0 to 1.2 G 0 as the length of the chain increases [4]. In addition, significant conductance oscillations are superimposed on top of this decreasing trend, which have been attributed to a parity effect. [4,6]. The rich behavior of platinum compared with gold arises from the larger number of conduction channels at the Fermi energy (E F ) due to the presence of d bands [7].To understand the structural, electronic and transport properties of platinum chains, we have performed a complete series of first principles simulations of platinum chains attached to platinum fcc leads. We have employed our newly developed code SMEAGOL [8,9], which calculates the density matrix and the transmission coefficients of a two probe device using the non-equilibrium Green's Function formalism (NEGF) [10]. The scattering potential is calculated self-consistently using the SIESTA implementation of density functional theory [11,12,13]. We have approximated the exchange and correlation potential by the Local Density Approximation (LDA), since we have found that provides a slightly more accurate description of the structural and conducting properties of bulk and infinite platinum chains than GGA [14]. We have not included in our calculations spin polarization which is only relevant for very stretched chains [15]. Our main result is that the most stable arrangement of platinum chains corresponds

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Conductance Oscillations in Zigzag Platinum Chains

et al. 2005

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“…4 display some differences in the charge distributions between different atoms. The charge distribution of the central chain for Al is reminiscent of that of monatomic chain structure 24 and has a directional character. The directional behavior is, however, less pronounced in the bonds forming between two atoms in the same pentagon and also between central chain atom and pentagon atom.…”

Section: B Energy Band Structure and Total Charge Densitymentioning

confidence: 99%

“…On the other hand, the binding energies of pentagonal structure are higher than the binding energies of various monatomic chain structures. In Table II [24]. 1D monatomic chain structures and bulk crystal, so its binding energy, E B =3.2 eV.…”

Section: A Optimized Structures and Energeticsmentioning

confidence: 99%

“…18,19,20,21,22,23,24,25,26 Whether the pentagonal structures predicted earlier by empirical methods 16,27,28,29 are common to other elements and can be understood from more fundamental principles have become an important issue. In this paper we address this question by using the first-principles plane wave calculations within the density functional theory.…”

Section: Introductionmentioning

confidence: 99%

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Pentagonal nanowires: A first-principles study of the atomic and electronic structure

et al. 2002

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We performed an extensive first-principles study of nanowires in various pentagonal structures by using pseudopotential plane wave method within the density functional theory. Our results show that nanowires of different types of elements, such as alkali, simple, transition and noble metals and inert gas atoms, have a stable structure made from staggered pentagons with a linear chain perpendicular to the planes of the pentagons and passing through their centers. This structure exhibits bond angles close to those in the icosahedral structure. However, silicon is found to be energetically more favorable in the eclipsed pentagonal structure. These quasi one dimensional pentagonal nanowires have higher cohesive energies than many other one dimensional structures and hence may be realized experimentally. The effect of magnetic state are examined by spin-polarized calculations. The origin of the stability are discussed by examining optimized structural parameters, charge density and electronic band structure, and by using analysis based on the empirical LennardJones type interaction. Electronic band structure of pentagonal wires of different elements are discussed and their effects on quantum ballistic conductance are mentioned. It is found that the pentagonal wire of silicon exhibits metallic band structure.

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“…A number of experimental and theoretical works have appeared on the geometry [13], electronic structure [14], Peierls instabilities [15], and conductance [16] of Al monowires. To our knowledge, although Pb nanowires a few dozen nanometers in diameter can be produced [17], sub-nanometer Pb monowires have not been synthesized or studied theoretically.…”

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Phonon band structure and electron-phonon interactions in metallic nanowires

Verstraete

Gonze

2006

Phys. Rev. B

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We present first-principles calculations of the phonon band structure and electron-phonon coupling in thin metallic nanowires. A full Brillouin zone analysis of the phonons is mandatory for the investigation of the nanowire structural stability: all the examined unstrained nanowires show instabilities whose wavevectors are located off the zone center. The unstable phonon modes are transverse, leading to a transition without a gap opening, in contrast with the usual Peierls distortion picture. Electron-phonon coupling yields orders-of-magnitude changes depending on the nanowire structure.PACS numbers: 71.15.Mb,73.21.Hb, Metallic nanowires consisting of a single chain of evenly spaced atoms (monowires) have long been a theorist's playground : they have inspired many model systems for electrons, phonons and their coupling. One dimensional (1D) metallic systems were shown to be unstable against longitudinal distortion (i.e. pairing) by Fröhlich[1] and Peierls [2] in the 50s. This is, however, a simplified situation, and more general distortions must be considered. Batra [3] showed that transverse distortions can give rise to a different type of transition, which does not open a gap around the Fermi level (a phenomenon he coined Gapless Peierls Transition -GPT). The consequences of electron-phonon coupling (EPC) in monowires have been the focus of recent studies, e.g.[4], in particular to determine the effect of phonons on conductivity. Peierls transitions have been seen in first-principles simulations of carbon nanotubes [5,6], and the issue of whether superconductivity can survive in 1D, despite Peierls transitions, is an open question. For both normal and superconductivity in 1D, understanding the interplay between structure, stability, and metallicity is essential for nanotechnological applications.Nanowires or nanotubes with diameters superior to a few nanometers are produced nowadays for many different atomic species. In the past decade, it has also become possible to experimentally create and examine wires comprising just a few or even one strand of atoms. The most impressive success has been with gold [7,8], but other metals have also been used in different experimental setups [9,10]. The potential applications of thin nanowires include integrating electronics on a molecular scale, improving scanning microscope tips, and increasing data storage densities if the wires are magnetic.In the first thin gold nanowires visualized with an electron microscope [7], a large distance was observed between neighboring atoms along the wire. This distance was explained using first-principles calculations[11] to be an average distance between second neighbors in a zigzag (ZZ) structure, obtained by a transverse period-doubling of the monowire. Structures with small angles ( 60 • ) between successive bonds have been found theoretically for many metals. Analogous ZZ structures, with an angle larger than 120 degrees, were proposed to be stable only for some metals (see e.g. Ref. 12).Although these striking examples point to the ...

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Structure of aluminum atomic chains

Cited by 72 publications

References 38 publications

Conductance Oscillations in Zigzag Platinum Chains

Conductance Oscillations in Zigzag Platinum Chains

Pentagonal nanowires: A first-principles study of the atomic and electronic structure

Phonon band structure and electron-phonon interactions in metallic nanowires

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