Isotope effects in lithium hydride and lithium deuteride crystals by molecular dynamics simulations.

Molecular dynamics (MD) simulations have been carried out to study isotope effects in lithium hydride and lithium deuteride crystals. Quantum effects on nuclear motion have been included through a quantum thermal bath (QTB). The interatomic forces were described either within the density functional theory (DFT) in the generalized gradient approximation (GGA) or by the phenomenological approach using the shell model.

Thermodynamics and kinetics of the Schottky defect at terraces and steps on the MgO(001) surface.

The Schottky defects at both the flat MgO(001) surface and the monatomic-step edge have been investigated by equilibrium molecular dynamics simulations. The formation enthalpy as a function of the distance between the Mg and O vacancies that form a Schottky defect have been calculated and discussed. We conclude that a step edge is a stable location for a vacancy.