The magnetic nucleus undergoes spin level splitting under the action of an external magnetic field. When absorbing external electromagnetic radiation, a transition of nuclear spin level will occur, resulting in nuclear magnetic resonance. In organic compounds, the electron cloud density around the various hydrogen nuclei in different structures and positions is different, resulting in a difference in resonance frequency, that is, a shift in the resonance absorption peak, called a chemical shift. Chemical Shift Calculation https://www.computabio.com/calculation-service-of-chemical-shift.html
