FIRST-PRINCIPLES INVESTIGATION OF NITROGEN NUCLEAR-QUADRUPOLE INTERACTIONS IN THE RDX (C3H6N6O6) SYSTEM

Using the first-principles Hartree-Fock procedure, the nuclear quadrup ole interaction parameters for N-14 nuclei in the ring nitrogens of th e RDX molecule are found to have the values 5.671, 5.808, and 5.839 MH z for the quadrupole coupling constants and 0.542, 0.557, and 0.562 fo r the asymmetry parameters, in good quantitative agreement with the co rresponding experimental values 5.735, 5.799, and 5.604 MHz and 0.6215 , 0.6146, and 0.6024, respectively, from nuclear quadrupole resonance measurements in the single crystal. Possible reasons for the small but significant difference in trend in the theoretical and experimental n uclear quadrupole interaction parameters over the three ring nitrogen atoms are discussed. The calculated nuclear quadrupole parameters for the N-14 nuclei of the three nitrogens of the three nitro groups and O -17 and H-2 nuclei at the oxygen and hydrogen sites are also presented , with the anticipation that they will be obtained experimentally in t he future for comparison with theory to obtain a more complete underst anding of the electron distribution over the whole molecule than is pr esently possible with ring nitrogen data.