INSTITUTO DE QUIMICA, FISICA DE LOS MATERIALES, MEDIOAMBIENTE Y ENERGIA
Unidad Ejecutora - UE
A Quantum-Mechanics Molecular-Mechanics scheme for extended systems
VERÓNICA MURIEL SANCHEZ; DAMIÁN SCHERLIS; HUNT DIEGO
JOURNAL OF PHYSICS CONDENSED MATTER
IOP PUBLISHING LTD
Lugar: Londres; Año: 2016 vol. 28 p. 335201 - 335201
We introduce and discuss a hybrid quantum-mechanics molecular-mechanics (QM-MM)approach for Car?Parrinello DFT simulations with pseudopotentials and planewaves basis,designed for the treatment of periodic systems. In this implementation the MM atoms areconsidered as additional QM ions having fractional charges of either sign, which providesconceptual and computational simplicity by exploiting the machinery already existing inplanewave codes to deal with electrostatics in periodic boundary conditions. With this strategy,both the QM and MM regions are contained in the same supercell, which determines theperiodicity for the whole system. Thus, while this method is not meant to compete with non-periodic QM-MM schemes able to handle extremely large but finite MM regions, it is shownthat for periodic systems of a few hundred atoms, our approach provides substantial savingsin computational times by treating classically a fraction of the particles. The performance andaccuracy of the method is assessed through the study of energetic, structural, and dynamicalaspects of the water dimer and of the aqueous bulk phase. Finally, the QM-MM scheme isapplied to the computation of the vibrational spectra of water layers adsorbed at the TiO2anatase (1 0 1) solid?liquid interface. This investigation suggests that the inclusion of a secondmonolayer of H2O molecules is sufficient to induce on the first adsorbed layer, a vibrationaldynamics similar to that taking place in the presence of an aqueous environment. The presentQM-MM scheme appears as a very interesting tool to efficiently perform molecular dynamicssimulations of complex condensed matter systems, from solutions to nanoconfined fluids todifferent kind of interfaces.