  We describe a simple scheme to perform phonon calculations with quantum Monte
Carlo (QMC) methods, and demonstrate it on metallic hydrogen. Because of the
energy and length scales of metallic hydrogen, and the statistical noise
inherent to QMC methods, the conventional manner of calculating force constants
is prohibitively expensive. We show that our alternate approach is nearly 100
times more efficient in resolving the force constants needed to calculate the
phonon spectrum in the harmonic approximation. This requires only the
calculation of atomic forces, as in the conventional approach, and otherwise
little or no programmatic modifications.
