  We present a simple methodology to compute the spontaneous volume
magnetostriction with first-principles calculations on the basis of the
magnetoelastic energy. This method makes use of deformations of the unit cell
only at the ferromagnetic state. Hence, it does not require the difficult
first-principles calculation of the equilibrium volume at the paramagnetic
state. To validate this methodology, we apply it to body-centered cubic Fe and
face-centered cubic Ni single crystals, finding consistent results with
experiment and previous first-principles calculations. The simplicity and
reliability of this approach could be exploited in the high-throughput
screening of spontaneous volume magnetostriction, as well as associated
quantities like isotropic magnetoelastic constants and isotropic
magnetostrictive coefficients.
