Understanding of Nuclear Quadrupole Interaction of $^{19}$F* and Binding Mechanism in Solid Fluorine at First-Principles Level

We have carried out a theoretical study of the nuclear quadrupole interaction (NQI) parameters of $^{19}$F* excited nuclear state in solid fluorine as well as the intermolecular binding of fluorine molecules in the solid. This is in continuation of our investigation [1] of the properties of solid halogens using the first-principles Hartree-Fock (HF) cluster procedure combined with many-body perturbation theory (MBPT), implemented by the Gaussian 03 set of programs. For the NQI parameters, the value of ($e^{2}$\textit{qQ/h}) obtained from our investigation for the $^{19}$F* excited nuclear state in solid fluorine is 120.9 MHz, which agrees with the experimental value 127.2 MHz, quoted in [2], within 5{\%} and the asymmetry parameter, $\eta $ is essentially zero. For obtaining ($e^{2}$\textit{qQ/h}) the value of the quadrupole moment, $Q$ for $^{19}$F* is taken from [3] as 0.072 x 10$^{28}$ m$^{2}$. As regards the binding of fluorine molecules in solid fluorine, our quantitative binding energy results show that the binding arises mainly from the van der Waals interaction obtained from intermolecular many-body effects with the one electron HF contribution being weak and repulsive in nature.\\[4pt] [1] M.M. Aryal et al., Hyperfine Interact, 176, 51 (2007). \\[0pt] [2] K.C.Mishra et al.,Phys. Rev.B25, 3389(1982).\\[0pt] [3] H. Barfuss et al., Phys. Lett. 90A, 33(1982).