Theoretical Sciences Unit (TSU): Recent submissions

  • Effective coordination as a predictor of adsorption energies: A model study of NO on Rh(100) and Rh/MgO(100) surfaces 
    Pushpa, Raghani; Ghosh, Prasenjit; Narasimhan, Shobhana; de Gironcoli, Stefano (American Physical Society, 2009-04)
    We have studied the adsorption of NO, and the coadsorption of N and O, on four physical and hypothetical systems: unstrained and strained Rh(100) surfaces and monolayers of Rh atoms on strained and unstrained MgO(100) ...
  • 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 ...
  • Elastic displacements and step interactions on metallic surfaces: Grazing-incidence x-ray diffraction and ab initio study of Au(332) 
    Prevot, G; Girard, Y; Repain, V; Rousset, S; Coati, A; Garreau, Y; Paul, Jaita; Mammen, Nisha; Narasimhan, Shobhana (American Physical Society, 2010-02)
    We have studied the energetics, relaxation, and interactions of steps on the Au(332) vicinal surface using a combination of grazing incidence x-ray diffraction, anisotropic linear elasticity theory, and ab initio ...
  • An ab initio study of polytetrahedral packing: the Al-Mg system 
    Narasimhan, Shobhana; Davenport, James W (American Physical Society, 1995-01-01)
    We have performed first-principles local-density-approximation calculations on aluminum-magnesium intermetallic compounds. Experimental studies of this system have shown that complex topologically close-packed structures ...
  • Surprises in the Physics of Metal Surfaces 
    Narasimhan, Shobhana (Indian Institute of Science, 2001)
    Metal surfaces sometimes exhibit surprisingly complex propenies, such as complicated surface structures, vibrational anisotropies, and a strongly enhanced surface anharmonicity, which result in drastic changes in properties ...
  • Ab initio calculation of the thermal properties of Cu: Performance of the LDA and GGA 
    Narasimhan, Shobhana; de Gironcoli, Stefano (American Physical Society, 2002-02-01)
    The thermal properties of bulk copper are investigated by performing ab initio density functional theory and density functional perturbation theory calculations and using the quasiharmonic approximation for the free energy. ...
  • 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 ...
  • Phonon softening and the anomalous thermal expansion of Ag(111) 
    Narasimhan, Shobhana (Elsevier Science BV, 1998-11-20)
    Ab-initio density functional theory calculations are performed to study how the structure and lattice dynamics of the Ag(111) surface change with temperature. It is found that the interlayer spacings near the surface ...
  • Double stripe reconstruction of the Pt(111) surface 
    Pushpa, Raghani; Narasimhan, Shobhana (Indian Academy of Sciences, 2003-01)
    We have studied the reconstruction of the Pt(111) surface theoretically, using a 2D generalization of the Frenkel-Kontorova model. The parameters in the model are obtained by performing ab initio density functional theory ...
  • Tuning the Morphology of Gold Clusters by Substrate Doping 
    Mammen, Nisha; Narasimhan, Shobhana; de Gironcoli, Stefano (American Chemical Society, 2011-03-09)
    The morphology of small metal clusters can have a big impact on their electronic, magnetic, and chemical properties. This has been shown earlier, for example, for Au(20) clusters on MgO(001), where planar and tetrahedral ...
  • Stars and stripes. Nanoscale misfit dislocation patterns on surfaces 
    Pushpa, Raghani; Narasimhan, Shobhana (International Union of Pure and Applied Chemistry, 2002-09)
    Close-packed metal surfaces and heteroepitaxial systems frequently display a structure consisting of regularly spaced misfit dislocations, with a network of domain walls separating face-centered cubic (fcc) and hexagonal ...
  • Competition between elastic and chemical effects in the intermixing of Co and Ag on Rh(111) 
    Imam, Mighfar; Marathe, Madhura; Narasimhan, Shobhana (Springer, 2008-11)
    We have performed ab initio density functional theory calculations to investigate the formation energy and the effects of low dimensionality and reduced coordination on the magnetic properties of pseudomorphically grown ...
  • 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 ...

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