Browsing by Author "Batra, I. P."

Now showing items 1-20 of 23

    • Absence of metallicity in Cs-GaAs(110): A Hubbard-model study 

      Gedik, Z.; Çıracı, Salim; Batra, I. P. (American Physical Society, 1993)
      Using an approximate solution of the Hubbard-model Hamiltonian, we are able to establish that the Cs-GaAs(110) system becomes a Mott insulator at submonolayer Cs coverages. We also provide a consistent interpretation of ...

    • Adhesive energy, force and barrier height between simple metal surfaces 

      Çıracı, Salim; Tekman, E.; Gökçedag, M.; Batra, I. P.; Baratoff, A. (1992)
      Using the self-consistent field pseudopotential method we calculated the adhesive energy, perpendicular and lateral forces and barrier height between two rigid A1(001) slabs modeling the sample and a blunt tip. We found ...

    • Adsorption site of alkali metal overlayers on Si(001) 2 × 1 

      Batra, I. P.; Çıracı, Salim (1992)
      The alkali metal semiconductor interfaces are currently being investigated by a variety of tools. Most studies to date at half a monolayer coverage have shown preference for either a quasi-hexagonal (H) site or a long-bridge ...

    • Calculations of STM linescans-general formalism 

      Ellialtioğlu, Ş.; Çıracı, Salim; Batra, I. P. (Pergamon Press, 1988)
      We have developed a formalism for calculating the line scans of the scanning-tunneling microscopy from the realistic substrate and tip wave functions. The tip wave functions are calculated self-consistently by using a ...

    • Conductance through a single atom 

      Mehrez, H.; Çıracı, Salim; Buldum, A.; Batra, I. P. (American Physical Society, 1997)
      In this paper we present an analysis of conduction through a single atom between two metal electrodes. Based on ab initio total-energy and electronic-structure calculations, and molecular-dynamics simulations using the ...

    • Conductance through atomic contacts created by scanning tunneling microscopy 

      Kiliç, Ç.; Mehrez, H.; Çıracı, Salim; Batra, I. P. (Elsevier, 1999)
      We investigate conductance through contacts created by pressing a hard tip, as used in scanning tunneling microscopy, against substrates. Two different substrates are considered, one a normal metal (Cu) and another a ...

    • Contact, nanoindentation, and sliding friction 

      Buldum, A.; Çıracı, Salim; Batra, I. P. (American Physical Society, 1998)
      This paper presents an atomic-scale study of contact, indentation, and subsequent pulling and dry sliding of a sharp and blunt metal tip on a metal surface. The evolution of atomic structure and the variation of perpendicular ...

    • Delta-Doping in strained (Si) / (Ge) superlattices 

      Çıracı, Salim; Batra, I. P.; Tekman, E. (American Physical Society, 1988)
      We present a comparative study of the pseudomorphic (Si)6/(Ge)6 and -doped (Si)3(Sb)(Si)2/(Ge)6 superlattices using the self-consistent pseudopotential method. The strained (Si)6/(Ge)6 superlattice has the lowest conduction-band ...

    • Effect of tip profile on atomic-force microscope images: a model study 

      Abraham, F. F.; Batra, I. P.; Çıracı, Salim (American Physical Society, 1988)
      Adopting the empirical silicon interatomic potential of Stillinger and Weber, we investigate the effect of the tip profile on the atomic-force microscope images for a prototype system, Si(001)-(2×1), and conclude that the ...

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

      Sen, P.; Batra, I. P.; Sivananthan, S.; Grein, C. H.; Dhar, N.; Çıracı, Salim (American Physical Society, 2003)
      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 (2 x 1) and rebonded (1 x 1) reconstructions ...

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

      Sen, P.; Çıracı, Salim; Batra, I. P.; Grein, C. H.; Sivananthan, S. (Elsevier, 2002)
      We perform first principles density functional calculations to investigate the adsorption of Te on the Si(0 0 1) surface from low coverage up to a monolayer coverage. At low coverage, a Te atom is adsorbed on top of the ...

    • Long-range order and segregation in semiconductor superlattices 

      Çıracı, Salim; Batra, I. P. (1987)
      Results of self-consistent energy-minimization calculations provide strong evidence that the ordered phases in epitaxially grown Ga1-xAlxAs and strained Si1-xGex alloys are metastable, in the sense that segregation into ...

    • Metallization of Silicon upon Potassium Adsorption 

      Çıracı, Salim; Batra, I. P. (1987)
      We report novel features of potassium deposition on a Si(111)-(2×1) surface as a function of coverage. The binding is ionic even at the saturation coverage without any overlayer metallization. Up to a threshold coverage, ...

    • Molecular-dynamics study of self-interstitials in silicon 

      Batra, I. P.; Abraham, F. F.; Çıracı, Salim (American Physical Society, 1987)
      Results of a molecular-dynamics computer simulation are presented for atomic relaxations and relaxation energies for self-interstitials in a silicon crystal. The Stillinger-Weber model potential containing two- and three-body ...

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

      Sen, P.; Gülseren, O.; Yildirim, T.; Batra, I. P.; Çıracı, Salim (American Physical Society, 2002)
      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 ...

    • Quantum effects in electrical and thermal transport through nanowires 

      Çıracı, Salim; Buldum, A.; Batra, I. P. (Institute of Physics Publishing, 2001)
      Nanowires, point contacts and metallic single-wall carbon nanotubes are one-dimensional nanostructures which display important size-dependent quantum effects. Quantization due to the transverse confinement and resultant ...

    • Quantum transport through one-dimensional aluminum wires 

      Batra, I. P.; Sen, P.; Çıracı, Salim (American Vacuum Society, 2002)
      Quantum conductance in narrow channels has been well understood by using the two-dimensional electron gas, a model system which has been realized in semiconductor heterojunctions. An essential property of this electron ...

    • Scanning-tunneling microscopy at small tip-to-surface distances 

      Çıracı, Salim; Batra, I. P. (1987)
      The scanning-tunneling microscopy (STM) of graphite at small tip-to-surface distances is investigated using the self-consistent-field pseudopotential method. We have calculated potential, charge density in the region between ...

    • Strain and dipole effects in covalent-polar semiconductor superlattices 

      Batra, I. P.; Çıracı, Salim; Özbay, Ekmel (1991)
      The energetics and electronic structure of lattice-matched (Ge)4/(GaAs)2 and strained, pseudomorphic (Si)4/(GaAs)2 (001) semiconductor superlattices have been studied with use of a self-consistent-field pseudopotential ...

    • Structure of aluminum atomic chains 

      Sen, P.; Çıracı, Salim; Buldum, A.; Batra, I. P. (American Physical Society, 2001)
      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 ...