Nuclear quantum effects in cubic silicon carbide from path-integral Monte Carlo simulations

We show how nuclear quantum effects shape the thermal and mechanical behavior of cubic silicon carbide (3C--SiC) under extreme conditions using path-integral Monte Carlo simulations. Our results indicate that quantum fluctuations account for over $80%$ of vibrational energy at cryogenic temperatures and persist above $800\phantom{\rule{0.28em}{0ex}}\mathrm{K}$ under pressure. Quantum softening lowers the bulk modulus by up to $6\phantom{\rule{0.28em}{0ex}}\mathrm{GPa}$ and induces negative thermal expansion at high pressure. Simulations reproduce experimental data within $0.5%$, demonstrating that path-integral Monte Carlo simulation is a robust tool for modeling covalent materials where classical methods fail.