Under the extended defect potential approximation, the electronic wave function which is a function of the PV defect energy has been derived using a tight binding Koster-Slater Green function technique. Taking the experimental value of the defect energy level as input parameter, the obtained wave function describes quantitatively the data of the electron paramagnetic resonance and electron-nuclear double resonance. Especially, the hyperfine interaction constants of the four nearest neighbor atoms around the vacancy given by the theory, are in good agreement with the experiment.