• Development of classical and quantum methods to simulate molecular clusters, molecular and ionic liquids, and for the description of correlation effects in electronic structure calculations.
• Investigation of the static and dynamical properties of hydrogen bonded clusters and condensed phases, with emphasis on the systems relevant for atmospheric chemistry.
• Development of simulation methods for the calculation of exact reaction and dissociation rates.
• Investigation of the electronic structure, interaction and reactivity of positron containing compounds.
• Investigation of the energetic and transport properties of pure and doped quantum clusters.
• Simulation of polymeric chains and polymer aggregates in solution.
• Catalytic processes in homogeneous and heterogeneous phases: Ziegler-Natta polymerization, organic redox reactions, alcohol upgrading and acid-base catalyzed reactions.

Past work within the Mella group focussed mainly on three key topics:

1. the development of statistical simulation techniques for the description of the energetic and dynamics of molecular aggregates (either clusters or liquids);
2. the generation of accurate model potentials describing interactions in molecular and ionic aggregates; and
3. the study of systems for which quantum effects and correlated dynamics play a fundamental role in defining the properties.

The three investigation areas mentioned above represent different aspects of a wider research theme aiming toward the understanding of intermolecular forces and their effects on the properties of molecular aggregates of various sizes. This is of fundamental interest in many areas of science, allowing, for instance, the prediction of thermodynamical and transport properties of liquids, the investigation of the solubility of molecular species in super-fluid droplets, and to estimate the stability and lifetime of molecular aggregates such as pure and doped water clusters. The latter are of extreme relevance for the description of atmospheric phenomena involving solvated species or requiring acid catalysis to take place.
The theoretical investigation of these subjects requires the use of advanced computational tools such as high-level electronic structure theory and statistical/molecular dynamics simulations, as well as the development of conceptual models to describe the relationship between molecular and aggregate properties. Thus, the group is also involved in developing and improving a wide range of computational tools, going from quantum stochastic simulations for electronic structure calculations to advanced methods to extract exact reaction rates from molecular dynamics.

More recent efforts have been directed toward understanding the chemistry induced by basic metal oxides (e.g. MgO) on organic species, investigating the catalytic features of transition metal complexes, studying the physico-chemical properties of polymeric chains, as well as the structure and energetics of quantum H2-ammonia aggregates.