Figure 1: Isotopic shift in lattice parameter for both LiH and LiD versus T. Experimental results and QTB-MD simulations. The interatomic forces were described within the density functional theory (DFT) in the generalized gradient approximation (GGA). (H. Dammak et al. J. Phys.: Condens. Matter 24 (2012) 435402)

Figure 2: Centroid position distributions of protons/deuterons in the crystallographic bc plane at 100~K in HF (upper part) and DF (lower part), as obtained from equilibrium QTB-PIMD trajectories.  The average  positions  of  the  F  atoms  are  shown  by  the  green  spheres. We evidence a symmetrization of H bonds and a Bmmb space group symmetry in HF. DF exhibits antiparallel structure (Pmnb space group symmetry) where deuterium hopping occurs through tunnel effect. We   employed   the   ABINIT   code and our simulations are performed in the framework of the projector augmented-wave (PAW) method. (H. Dammak et al. Phys. Chem. Chem. Phys. 21 (2019) pp.3211-3217)