Vanadium(v) is an extremely rare and precious metal, mainly used in aerospace equipment and new energy construction. However, an efficient, simple, and environmentally friendly method for separating V from its compounds is still lacking. In this study, we used first-principles density functional theory to analyse the vibrational phonon density of states of ammonium metavanadate and simulated its infrared absorption and Raman scattering spectra. By analysing the normal modes, we found that the V-related vibration has a strong infrared absorption peak at 711 cm−1, while other significant peaks above 2800 cm−1are from N–H stretching vibrations. Therefore, we propose that providing high-power terahertz laser radiation at 711 cm−1may facilitate the separation of V from its compounds through phonon–photon resonance absorption. With the continuous progress of terahertz laser technology, this technique is expected to be developed in the future, and it may offer new technological possibilities.