Theoretical Sciences Unit (TSU): Recent submissions

  • Effect of coordination on bond properties: A first principles study 
    Paul, Jaita; Narasimhan, Shobhana (Springer, 2008-06)
    We have used density functional theory to obtain the binding curves for a variety of hypothetical periodic structures of Al, Si, Pb, So and Au. Upon examining the resulting database of results for equilibrium bond lengths ...
  • Surprises in the physics of metal surfaces 
    Narasimhan, Shobhana (Indian Institute of Science, 2001-01)
    Metal surfaces sometimes exhibit surprisingly complex properties, such as complicated surface structures, vibrational anisotropies, and a strongly enhanced surface anharmonicity, which result in drastic changes in properties ...
  • Effect of coordination on bond properties: A first principles study 
    Paul, Jaita; Narasimhan, Shobhana (Springer, 2008-06)
    We have used density functional theory to obtain the binding curves for a variety of hypothetical periodic structures of Al, Si, Pb, So and Au. Upon examining the resulting database of results for equilibrium bond lengths ...
  • Anharmonic self energies of phonons in silicon 
    Narasimhan, Shobhana; Vanderbilt, David (American Physical Society, 1991-02-15)
    We have carried out a realistic ab initio calculation of the contribution of cubic anharmonicity to the inverse lifetime GAMMA and the frequency shift DELTA of phonons in silicon. The cubic coupling constants for phonons ...
  • Reversed anisotropies and thermal contraction of fcc (110 ) surfaces 
    Narasimhan, Shobhana (American Physical Society, 2001-09-10)
    The observed anisotropies of surface vibrations for unreconstructed fcc metal (110) surfaces are often reversed from the “common sense” expectation; for example, atoms in the top layer have larger amplitudes of vibration ...
  • Exchange–correlation errors at harmonic and anharmonic orders: the case of bulk Cu 
    Pushpa, Raghani; Narasimhan, Shobhana (Indian Academy Of Sciences, 2003-01)
    As an aid towards improving the treatment of exchange and correlation effects in electronic structure calculations, it is desirable to have a clear picture of the errors introduced by currently popular approximate ...
  • Bond stiffening in small nanoclusters and its consequences for mechanical and thermal properties 
    Pushpa, Raghani; Waghmare, Umesh; Narasimhan, Shobhana (American Physical Society, 2008-01)
    We have used density functional perturbation theory to investigate the stiffness of interatomic bonds in small clusters of Si, Sn, and Pb. As the number of atoms in a cluster is decreased, there is a marked shortening and ...
  • Symmetries, vibrational instabilities, and routes to stable structures of clusters of Al, Sn, and As 
    Pushpa, Raghani; Narasimhan, Shobhana; Waghmare, Umesh (American Institute of Physics, 2004-09-15)
    We investigate the stability of small clusters using density functional theory to compute the total energy, forces, and vibrational frequencies using linear response. We exhibit an efficient and computationally low-cost ...
  • Effective coordination number: A simple indicator of activation energies for NO dissociation on Rh(100) surfaces 
    Ghosh, Prasenjit; Pushpa, Raghani; de Gironcoli, Stefano; Narasimhan, Shobhana (American Physical Society, 2009-12)
    We have used density-functional theory to compute the activation energy for the dissociation of NO on two physical and two hypothetical systems: unstrained and strained Rh(100) surfaces and monolayers of Rh atoms on strained ...
  • Stress, strain, and charge transfer in Ag/Pt(111) : A test of continuum elasticity theory 
    Narasimhan, Shobhana (American Physical Society, 2004-01)
    We study the validity of continuum elasticity theory for the heteroepitaxial Ag/Pt(111) system, by performing ab initio calculations of the structure, stress, and elastic constants. Interlayer separations after the deposition ...
  • Multipolar polarizabilities and Rydberg states 
    Krishnagopal, S; Narasimhan, Shobhana; Patil, S H (American Institute of Physics, 1985-06-12)
    We have calculated multipolar polarizabilities for several atoms and ions, using some semiclassical relations and incorporating the correct asymptotic behavior in the electronic densities. We have also obtained simple ...
  • Size dependence of structural, electronic, elastic, and optical properties of selenium nanowires: A first-principles study 
    Kahaly, Mousumi Upadhyay; Ghosh, Prasenjit; Narasimhan, Shobhana; Waghmare, Umesh V (American Institute of Physics, 2008-01-28)
    We have studied the structural, elastic, and optical properties of selenium nanowires, as well as bulk selenium, by performing first-principles density functional theory calculations. The nanowires are structurally similar ...
  • Mixing and magnetic properties of surface alloys: The role of the substrate 
    Marathe, Madhura; Imam, Mighfar; Narasimhan, Shobhana (Elsevier Science BV, 2009-10-30)
    In this paper, we have performed ab initio density functional theory calculations to compare the miscibility and magnetic properties of two-dimensional binary surface alloys of the form MxN1-x (M = Fe or Co; N = Pt, Au, ...
  • Lifting of Ir{100} reconstruction by CO adsorption: An ab initio study 
    Ghosh, Prasenjit; Narasimhan, Shobhana; Jenkins, Stephen J; King, David A (American Institute of Physics, 2007-06-28)
    The adsorption of CO on unreconstructed and reconstructed Ir{100} has been studied, using a combination of density functional theory and thermodynamics, to determine the relative stability of the two phases as a function ...
  • Elastic-Stress Domains and the Herringbone Reconstruction on Au(111) 
    Narasimhan, Shobhana; Vanderbilt, David (American Physical Society, 1992-09-07)
    We suggest that the herringbone reconstruction of the Au(111) surface results from the spontaneous formation of "stress domains." The surface is described theoretically by a 2D Frenkel-Kontorova model. Upon including ...
  • Symmetries, vibrational instabilities, and routes to stable structures of clusters of Al, Sn, and As 
    Pushpa, Raghani; Narasimhan, Shobhana; Waghmare, Umesh (Ameriacn Institute of Physics, 2004-09-15)
    We investigate the stability of small clusters using density functional theory to compute the total energy, forces, and vibrational frequencies using linear response. We exhibit an efficient and computationally low-cost ...
  • Interplay between bonding and magnetism in the binding of NO to Rh clusters 
    Ghosh, Prasenjit; Pushpa, Raghani; de Gironcoli, Stefano; Narasimhan, Shobhana (American Institute of Physics, 2008-05-12)
    We have studied the binding of NO to small Rh clusters, containing one to five atoms, using density functional theory in both spin-polarized and non-spin-polarized forms. We find that NO bonds more strongly to Rh clusters ...
  • Electronic properties of Fe clusters on a Au(111) surface 
    Delga, Alexandre; Lagoute, Jerome; Repain, Vincent; Chacon, Cyril; Girard, Yann; Marathe, Madhura; Narasimhan, Shobhana; Rousset, Sylvie (American Physical Society, 2011-07-21)
    The electronic states of self-organized Fe nanoislands on a Au(111) surface have been investigated using low-temperature scanning tunneling microscopy and spectroscopy. We show that the local density of states is dominated ...
  • Comparison between s- and d-electron mediated transport in a photoswitching dithienylethene molecule using ab initio transport methods 
    Odell, Anders; Delin, Anna; Johansson, Borje; Ulman, Kanchan; Narasimhan, Shobhana; Rungger, Ivan; Sanvito, Stefano (American Physical Society, 2011-10-03)
    The influence of the electrode's Fermi surface on the transport properties of a photoswitching molecule is investigated with state-of-the-art ab initio transport methods. We report results for the conducting properties of ...
  • Reconstruction of Pt(111) and domain patterns on close-packed metal surfaces 
    Pushpa, Raghani; Narasimhan, Shobhana (The American Physical Society, 2003-05-23)
    We have studied the reconstruction of Pt(111) theoretically using a two-dimensional Frenkel-Kontorova model for which all parameters have been obtained from ab initio calculations. We find that the unreconstructed surface ...

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