Sudha Srinivasa, S. B. Sulaimanb, N. Sahooc,d and T. P. Dasd *
a Department of Physics, Central Michigan University,
Mount Pleasant, MI, 48859, USA
b Department of Physics and Information Technology Centre, Universiti Sains Malaysia, Minden 11800, Penang, Malaysia
c Department of Radiation Oncology, The Albany Medical College, Albany, NY, 12208, USA
d Department of Physics, State University of New York at Albany, Albany, NY, 12222, USA
* Corresponding Author: FAX 1-(518)-442-5260
In our previous published work on La2CuO4, we have studied the 63Cu nuclear quadrupole and magnetic hyperfine interactions [1,2] and the magnetic hyperfine interaction for positive muon trapped in La2CuO4  using the Hartree-Fock Cluster Procedure . In the present work, we would like to discuss results of our investigation on 17O nuclear quadrupole interactions in this compound. A thorough understanding of the electronic structure and hyperfine properties (both nuclear quadrupole and magnetic) in the pure compound is very important in order to have confidence in the extension of the same methods of investigation to systems containing impurities, especially in the range of concentrations where charge and spin stripe structures are important.
From the results of our investigation, the e2qQ and h for the planar 17O nuclei come out as – 4.5 MHz and 0.40 respectively, in good agreement with the experimental values  of 4.67 MHz (magnitude) and 0.36 in La2-xSrxCuO4 with the smallest value of x studied namely 0.0375. For the apical 17O nucleus, our calculated e2qQ is -2.3 MHz as compared to the experimental value of 1.3 MHz (magnitude) . The calculated values of h is very close to zero as is also the experimental value, because of the near tetragonal symmetry at this site. Possible reasons, such as the influence of the spin-orbit interaction  at the neighboring copper site as well as at the oxygen site itself on the electric field gradient at 17O at the apical site, and the contributions to q at 17O from the dipole moments  on the highly deformable O-2 ions at apical sites (outside the cluster used for the Hartree-Fock calculations of the electron distribution near the 17O nucleus) where there is no inversion symmetry. The apical 17O site is expected to be more affected by the influence of the dipole moments at apical oxygens, because of its proximity to a larger number of these dipole moments than is the case for the planar sites. The effects of the point charges on the ions outside the clusters used for the planar and apical 17O studies are already included through their coulomb potentials acting on the electrons in the cluster.
 S. B. Sulaiman, N. Sahoo, T. P. Das, O. Donzelli, E. Torikai
and K. Nagamine, Phys. Rev. B44, 7028 (1991).
 S. B. Sulaiman, N. Sahoo, T. P. Das and O. Donzelli, Phys. Rev. B45, 7383 (1992).
 S. B. Sulaiman, N. Sahoo, Sudha Srinivas, F. Hagelberg, T. P. Das, E. Torikai and K. Nagamine, Phys. Rev. B49, 9879 (1994).
 See for instance: D. W. Mitchell et al., Phys. Rev. B48, 16449 (1993).
 K. Ishida, Y. Kitaoka, G. Zheng and K. Asayama, J. Phys. Soc. Japan, 60, 3516 (1991).
 J. N. Roy, S. K. Mishra, K. C. Mishra and T. P. Das, J. Chem. Phys. 90, 7273 (1989).
 R. R. Sharma and T. P. Das, J. Chem. Phys. 41, 3582 (1964).
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