Geometry and vibration properties for monoclinic zirconium oxide were studied using Gaussian basis sets and LDA, GGA, and B3LYP functionals. Bond angles, bond lengths, lattice parameters, and Raman frequencies were calculated and compared to experimental values. Bond angles and lengths were found to agree within experimental standard deviations. The B3LYP gave the best performance of all three functionals with a percent error of 1.35% for the lattice parameters while the average difference between experimental and calculated Raman frequency values was -3 cm-1. The B3LYP functional was then used to assign the atomic vibrations causing each frequency mode using isotopic substitution of 93.40Zr for 91.22Zr and 18.00O for 16.00O. This resulted in seven modes assigned to the Zr atom, ten modes to the O atom, and one mode being a mixture of both.