Phonons of metallic hydrogen with quantum Monte Carlo

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 modification.

Automated summary

This work proposes a simple scheme to perform phonon calculations with quantum Monte Carlo (QMC) methods and applies it to metallic hydrogen. The conventional method of calculating force constants in metallic hydrogen is computationally expensive due to its energy and length scales, as well as statistical noise inherent in QMC methods. The authors demonstrate an alternate approach that is nearly 100 times more efficient in resolving the force constants required for calculating the phonon spectrum in the harmonic approximation, requiring only the calculation of atomic forces without significant programmatic modification.