Jaita Paul

Publications (3)0 Total impact

• Article: Effect of coordination on bond properties: A first principles study

  Jaita Paul, Shobhana Narasimhan
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  ABSTRACT: We have used density functional theory to obtain the binding curves for a variety of hypothetical periodic structures of Al, Si, Pb, Sn and Au. Upon examining the resulting database of results for equilibrium bond lengths and radial force constants (within a nearest-neighbour model), we find that both decrease smoothly as coordination is reduced. The effect of dimensionality appears to be small. We find that the force constants at equilibrium vary as the inverse eighth power of the equilibrium bond length. We also find evidence that the force constants are sensitive only to the bond length, and not to the coordination number. We believe these results will be useful in formulating interatomic potentials, e.g., for nanosystems.
  Bulletin of Materials Science - BULL MATER SCI. 01/2008; 31(3):569-572.
• Article: Elastic displacements and step interactions on metallic surfaces: Grazing-incidence x-ray diffraction and ab initio study of Au (332)

  G. Prévot, Y. Girard, V. Repain, S. Rousset, A. Coati, Y. Garreau, Jaita Paul, Nisha Mammen, Shobhana Narasimhan
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  ABSTRACT: 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 density-functional theory. We find that the initial force distribution on a bulk-truncated surface, as well as the resulting pattern of atomic relaxations, can be reproduced excellently by a buried dipole elastic model. The close agreement obtained between experimental and calculated x-ray diffraction profiles allows us to precisely determine the value of the elastic dipole density at the steps. We also use these results to obtain an experimental estimate of the surface stress on an unreconstructed Au(111) facet, τAu(111)=2.3±0.4 Nm−1, and the value of the step-step elastic interaction energy A=950±150 meV Å.
  Phys. Rev. B. 81(7).
• Article: Elastic displacements and step interactions on metallic surfaces: GIXD and ab initio study of Au(332)

  Geoffroy Prévot, Yann Girard, Vincent Repain, Sylvie Rousset, Alessandro Coati, Yves Garreau, Jaita Paul, Nisha Mammen, Shobhana Narasimhan
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  ABSTRACT: 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 (GIXD), anisotropic linear elasticity (ALE) theory, and ab initio density functional theory (DFT). We find that the initial force distribution on a bulk-truncated surface, as well as the resulting pattern of atomic relaxations, can be reproduced excellently by a buried dipole elastic model. The close agreement obtained between experimental and calculated X-ray diffraction profiles allows us to precisely determine the value of the elastic dipole density at the steps. We also use these results to obtain an experimental estimate of the surface stress on an unreconstructed Au(111) facet, 2.3+/-0.4 Nm-1, and the value of the step-step elastic interaction energy: 950 +/- 150 meV.Å.
  Physical Review B.