Identification of oxygen diffusion mechanisms in NdAEBaInO (AE = Ca, Sr, Ba) compounds through molecular dynamics.

Molecular dynamics simulations have been widely adopted to study oxygen ion diffusion mechanisms in materials for application in solid oxide fuel cells. Indeed, understanding the fundamental aspects of oxygen diffusion is important to develop new materials for this application. In this work, Nd1-xAExBaInO4-x/2 (AE = Ca, Sr, Ba) compounds have been studied by MD simulations focusing on oxygen diffusion mechanisms.

On the Use of Quantum Thermal Bath in Unimolecular Fragmentation Simulation.

In the present work, we have investigated the possibility of using the quantum thermal bath (QTB) method in molecular simulations of unimolecular dissociation processes. Notably, QTB is used in introducing nuclear quantum effects with a computational time, which is basically the same as in Newtonian simulations. At this end, we have considered the model fragmentation of CH for which an analytical function is present in the literature.

Isotope effect on hydrogen bond symmetrization in hydrogen and deuterium fluoride crystals by molecular dynamics simulation.

The isotope effect on the collective proton/deuteron transfer in hydrogen and deuterium fluoride crystals has been investigated at 100 K by ab initio quantum-thermal-bath path-integral molecular dynamics (QTB-PIMD) simulation. The deuterons within a planar zigzag chain of the orthorhombic structure simultaneously flip between covalent and hydrogen bonds due to the barrier crossing through tunnelling. The height of the corresponding static barrier normalized for one deuteron is 29.

Zero-Point Energy Leakage in Quantum Thermal Bath Molecular Dynamics Simulations.

The quantum thermal bath (QTB) has been presented as an alternative to path-integral-based methods to introduce nuclear quantum effects in molecular dynamics simulations. The method has proved to be efficient, yielding accurate results for various systems. However, the QTB method is prone to zero-point energy leakage (ZPEL) in highly anharmonic systems.

Quantum Thermal Bath for Path Integral Molecular Dynamics Simulation.

The quantum thermal bath (QTB) method has been recently developed to account for the quantum nature of the nuclei by using standard molecular dynamics (MD) simulation. QTB-MD is an efficient but approximate method when dealing with strongly anharmonic systems, while path integral molecular dynamics (PIMD) gives exact results but in a huge amount of computation time. The QTB and PIMD methods have been combined in order to improve the PIMD convergence or correct the failures of the QTB-MD technique.

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.

Quantum thermal bath for molecular dynamics simulation.

Molecular dynamics (MD) is a numerical simulation technique based on classical mechanics. It has been taken for granted that its use is limited to a large temperature regime where classical statistics is valid. To overcome this limitation, the authors introduce in a universal way a quantum thermal bath that accounts for quantum statistics while using standard MD.

Full Tensorial characterization of PZN-12%PT single crystal by resonant ultrasound spectroscopy.

An experimental setup based on the electrical excitation of a piezoelectric sample is proposed for resonant ultrasound spectroscopy measurements. The detection of the mechanical vibrations is performed by means of a laser interferometer. At the same time, the free vibrations of piezoelectric parallelepipeds of tetragonal and hexagonal symmetries are modeled taking into account the effect of the sample metalization.