Quantum localization of hydrogen atoms in solids

Quantum distributions of hydrogen-like atoms in solids were investigated theoretically by the first-principles path-integral molecular dynamics (FP-PIMD) method, in which interatomic forces are calculated precisely based on the density functional theory. Some distributions are qualitatively different from those obtained by conventional simulations with classical treatment of protons. Interestingly, quantum fluctuations sometimes cause localization of the nuclei. The mechanism of this ‘quantum localization’ is intuitively explained by considering characteristic potential energy surfaces.