Quantum mechanics cannot calculate the frequency of 9,192,631,770 Hz from first principles, as this frequency is a defined value rather than a calculable one. The second is a man-made quantity chosen by the BIPM and could theoretically be any number of oscillations of the cesium hyperfine transition. Attempts to derive this frequency from pre-1967 definitions are also futile due to the complexity of the problem, which involves multiple bodies and lacks classical solutions. Additionally, the uncertainty in the mass of the electron is too significant to yield precise results. Thus, while quantum mechanics can calculate energy levels, it cannot achieve the precision required to match the defined frequency of the second.