Research lines

de Lara-Castells' Group of Ab-initio Simulations in Helium, Semiconductor Oxide Surfaces and Carbon Nanostructures

This group belongs to the Department of Atomic, Molecular and Cluster Physics at the Instititute of Fundamental Physics at Madrid.

Our research is aimed at extending and applying the ab-initio methodology developed within the framework of the electronic structure of molecular systems, to include: 1) quantum nuclear effects in weakly-bound systems, and nuclear quantum delocalization in electronic structure calculations; 2) electronic correlation effects in extended systems including (semiconductor) oxide surfaces and carbon nanostructures (e.g., adsorbate-surface dispersion-dominated interactions and/or including excited states).

Specific on-going projects include the ab-initio simulations of 1) the molecular spectroscopy of doped helium and para-hydrogen clusters under different conditions, 2) the (helium-mediated) soft-landing deposition of metal clusters on technologically relevant semiconductor and carbon-based surfaces, and 3) the molecular photoreactivity in semiconductor oxide surfaces.

Our research involves the collaboration with European research groups of the cooperative networks CODECS (CMST COST Action CM1002) and MOLIM (CMST COST Action CM1405), and transnational collaborations. 

Objectives

Our general objective is to extend the ab-initio methodology developed for the understanding of the electronic structure of molecular systems 1) to unravel nuclear quantum effects in complex solvent environments; 2) to include electronic correlation effects in complex systems implying the condensed matter. Our specific objectives can be classified according to the systems under study as:

1) Ab-initio simulation of the molecular spectroscopy in helium (and para-hydrogen) clusters. We have extended ab-initio methods to the description of nuclear quantum effects in doped helium (Phys. Chem. Chem. Phys. 15 (2013) 12) and para-hydrogen (e.g., J. Phys. Chem. Lett. 2 (2011) 2145) clusters. These methods have been applied to the spectroscopy of molecules solvated by helium (e.g., Chem. Phys. Lett. 555 (2013) 12). Our aim is to complement existing techniques by accounting for (bosonic and/or fermionic) nuclear spin statistical effects, and by describing the excited states of quantum solvents with a similar accuracy to that of the ground state, and to study nuclear delocalization effects beyond the Born-Oppenheimer approximation (e.g., J. Chem. Phys. 138 (2013) 184113). Most recently, our efforts are being driven to pure helium clusters in confining potentials (e.g., inside carbon nanotubes).

 



2) Ab-initio simulation of molecular photoreactivity in semiconductor surfaces. First-principle studies of excited states on extended (semiconductor) metal oxides are required for a better understanding of their photocatalytic properties. In order to achieve this goal, it is necessary to calculate the properties of the molecule-surface complex in both the ground and the excited electronic states (J. Chem. Phys. 118 (2003) 5098) as well as their couplings with the substrate elementary excitations. Through the application of ab-initio techniques for molecular systems, it is possible to apply a rich tool box of different methods to accurately treat excited states. However, these methods can not deal with the infinite (periodic) environment. In order to include it, we have worked in an embedding technique (J. Phys. Chem. C 115 (2011) 17540), having been successfully applied to bulk titanium dioxide.

 

 


(3) Ab-initio simulation of the soft-landing of metallic species on technologically relevant surfaces. The photocatalytic and/or catalytic properties of surfaces can be improved through the controlled deposition of metallic nanoparticles. An innovative experimental technique uses helium nanodroplets as the carriers of the embedded nano-particles to the target surface in soft-landing conditions. The ab-initio simulation of this process requires the calculation of realistic potentials accounting for the dispersion-dominated interaction of the quantum solvent with the surface (e.g., J. Chem. Phys. Communications 141 (2014) 151102) as well as the inclusion of nuclear quantum effects into the (J. Chem. Phys. Communications 142 (2015) 131101)dynamics (e.g., J. Chem. Phys. 136 (2012) 124703/1-14). Very recently, the first theoretical evidences of the soft-landing process have been reported within the framework of our collaboration with the Universities of Barcelona, Paris-Est, and Stuttgart (J. Chem. Phys. Communications 142 (2015) 131101)
. A special ab-initio-based scheme has been recently proposed to calculate the necessary van der Waals-dominated adsorbate-surface interactions  (e.g., J. Chem. Phys. 143 (2015) 102804).