Quantum Thermal Bath for Path Integral Molecular Dynamics Simulation

Thermostat quantique pour la méthode de dynamique moléculaire utilisant les intégrales de chemin

Fabien Brieuc (1) , Hichem Dammak (1) , Marc Hayoun (2)

1 SPMS - Laboratoire Structures, Propriétés et Modélisation des solides
2 LSI - Laboratoire des Solides Irradiés - Irradiated Solids Laboratory

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 for dealing with strongly anharmonic systems, while path integral molecular dynamics (PIMD) gives exact results 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. A new power spectral density of the random force within the QTB has therefore been developed. A modified centroid-virial estimator of the kinetic energy, especially adapted to QTB-PIMD, has also been proposed. The method is applied to selected systems: a one-dimensional double well system, a ferroelectric phase transition, and the position distribution of an hydrogen atom in a fuel cell material. The advantage of the QTB-PIMD method is its ability to give exact results with a more reasonable computation time for strongly anharmonic systems. †

Domaines: Physique [physics]; Matière Condensée [cond-mat]; Science des matériaux [cond-mat.mtrl-sci]; Mécanique statistique [cond-mat.stat-mech]

Fabien Brieuc, Hichem Dammak, Marc Hayoun. Quantum Thermal Bath for Path Integral Molecular Dynamics Simulation. Journal of Chemical Theory and Computation, 2016, 12 (3), pp.1351 - 1359. ⟨10.1021/acs.jctc.5b01146⟩. ⟨hal-01932606⟩