Prasenjit Sen

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

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 effects of magnetic state are examined by spin-polarized calculations. The origin of the stability is discussed by examining optimized structural parameters, charge density and electronic band structure, and by using analysis based on the empirical Lennard-Jones-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.

Structure of aluminum atomic chains

First-principles density-functional calculations reveal that aluminum can form planar chains in zigzag and ladder structures. The most stable one has equilateral triangular geometry with four nearest neighbors; the other stable zigzag structure has wide bond angle and allows for two nearest neighbors. An intermediary structure has the ladder geometry and is formed by two strands. While all these planar geometries are more favored energetically than the linear chain, the binding becomes even stronger in nonplanar geometries. We found that by going from bulk to a chain the character of bonding changes and acquires directionality. The conductance of zigzag and linear chains is

Electronic structure of Te- and As-covered Si(211)

{4e}^{2}/h

Te covered Si(001): A variable surface reconstruction

under ideal ballistic conditions.

Finite temperature studies of Te adsorption on Si(0 0 1)

Electronic and atomic structures of the clean and As- and Te-covered Si(211) surface are studied using pseudopotential density-functional method. The clean surface is found to have

Formation of an ordered Si dimer structure on HfB 2 ( 0001 )

(2\ifmmode\times\else\texttimes\fi{}1)

Adsorption of Si on HfB_2(001) - a Compuational and STM Analysis

and rebonded

Electronic and Structural Properties of Nanowires with Pentagonal Cross Section

(1\ifmmode\times\else\texttimes\fi{}1)

Theoretical Study of Adsorption of Ba on Si(100)-(2x1)

reconstructions as stable surface structures, but no

Adsorption of Te on the Si(001) Surface

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