# Research

At the Kumpula campus, top research is being carried out in many of the disciplines included in the programme, such as theoretical particle physics, cosmology, computational material physics, aerosol physics, mathematical physics, inverse problems, theoretical chemistry, laser spectroscopy, and algorithm theory. The instruction in the Master’s Programme in Theoretical and Computational Methods is given by researchers in these groups. The programme will give you a solid basis for continuing with postgraduate studies and research in one of these areas.

The programme cooperates with the Helsinki Institute of Physics (HIP) and the Helsinki Institute for Information Technology (HIIT) and collaborates with the Academy of Finland Centres of Excellence in Analysis and dynamics research, Inverse problems and Atmospheric science.

The Computational Field Theory Group studies properties of field theories in particle physics and cosmology using large-scale numerical simulations. Recent research topics include e.g. beyond the standard model physics, quantum chromodynamics, phase transitions and generation of gravitational waves.

The Mathematical Physics Research Group works on mathematically rigorous analysis of a wide variety of problems including quantum and statistical field theories, transport and kinetic theory of phonons, waves and quantum evolution, open quantum systems, turbulence and stochastic evolution equations, such as the Schramm–Loewner evolution.

The Computational Aerosol Physics Research Group applies computational and theoretical methods to understand cluster and particle formation for atmospherically relevant molecules. The techniques involve molecular dynamics, Monte Carlo simulations and cluster size distribution dynamics with molecular interactions taken either from quantum chemical models or thermodynamics.

The Computational Atmospheric Chemistry Group studies the chemical reactions of atmospheric condensable vapors and their precursors using computational methods, with emphasis on reactive sulfur- and nitrogen-containing molecules, and on atmospheric autoxidation reactions of complex organic molecules. The foundation is provided by a large variety of quantum chemical methods, from state-of-the-art multireference configuration interaction (MRCI) and coupled cluster (CC) methods to density functional theory (DFT). Molecular-level reaction mechanisms and potential energy surfaces are then used as input for reaction dynamic calculations in order to obtain information on real reaction rates in the atmosphere.

The Molecular Spectroscopy and Theoretical Chemistry Group's research interests include the following: Investigation of spectroscopic properties of atmospherically important molecules and complexes, such as water clusters which play a key role in atmospheric processes such as cloud formation, the greenhouse effect and acid rain catalysis. An accurate and efficient description of long distance forces (van der Waals dispersion interactions) in molecular clusters and nanoparticles. Molecular dynamics studies of chemical reactions, scattering, ionization and solvation effects of acids interacting with ice, mineral, and wet surfaces. Development of theoretical and computational tools describing internal molecular motions.

In order to understand experimental results modeling of the studied phenomena is needed. Computational methods are used widely in the field of materials physics. The Group of Computational Physics has in its use methods covering many time and length scales, starting from quantum mechanical calculations at atomic level and picosecond time scales and up to continuum modeling of materials and macroscopic times scales. Initially modeling was used in connection with ion beam physics experiments that are far from the thermodynamical equilibrium. Currently, modeling is also used in many equilibrium phenomena. The group has in its disposal computer clusters located at the Kumpula campus area and the supercomputers at the Finnish IT center for science, CSC.

Non-standard methods to evaluate large and structured sums of products – especially methods involving moderately-exponential-time algorithms – have great prospects to significantly advance the state of the art in algorithm theory and computational statistics. The Sums of Products Research Group's mission is to implement this vision by studying (a) algorithm theory of computing sums of products, (b) sums of products in computational statistics, and (c) applications in science and technology.

The Centre of Excellence in Analysis and Dynamics Research is a collaboration of several mathematics research groups at the Universty of Helsinki, University of Jyväskylä, and University of Oulu. The research covers a wide spectrum of mathematical analysis and its applications: dynamical systems, fractal geometry, random geometry, partial differential equations and turbulence, statistical mechanics and mathematical models of biological evolution.

The Centre of Excellence in Atmospheric Science – From Molecular and Biological processes to the Global Climate – includes 235 scientists working in the fields of physics, chemistry, biology and meteorology at the University of Helsinki, University of Eastern Finland (Kuopio), and at the Finnish Meteorological Institute. Our work is based on a network of field stations producing extensive long-term data on atmospheric properties and ecological mass fluxes in different types of environments and regions, including Arctic, boreal and tropical ecosystems, and on focused experiments and modeling aimed at understanding the observed patterns.