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Finnish CoE of Computational Molecular Science Laskennallisen molekyylitutkimuksen huippuyksikkö Spetsenheten för datorstödd molekylforskning. Kanslerin vierailu 4.3.2008. Faculty of Science . Government labs: - Meteorology - Marine Research Including students, about 9000 people.
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Finnish CoE of Computational Molecular Science Laskennallisen molekyylitutkimuksen huippuyksikköSpetsenheten för datorstödd molekylforskning Kanslerin vierailu 4.3.2008
Faculty of Science. Government labs: - Meteorology - Marine Research Including students, about 9000 people. Entire UoH: 38000 students. 8 national CoE:s, including ’Finnish Centre of Excellence of Computational Molecular Science’ (2006-2011). (CMS) The Kumpula Campus, University of Helsinki, Finland • CMS groups: Pyykkö-Sundholm,Halonen, Räsänen, Vaara, Nordlund. About 60 people. • Nordic ’umbrella’ of CoE:s.
Some key people employed on CMS monies Group Pyykkö: Coordinator Dage Sundholm. Graduate students Patryk Zaleski-Ejgierd and Cong Wang Group Halonen: Post-docs Delia Fernandez, Qinghua Ren. Graduate students Tommi Lantta, Matti Rissanen, Teemu Salmi, Markku Vainio. Group Nordlund: Senior scientists Mikko Hakala, Arkady Krasheninnikov, Flyura Djurabekova. Graduate students Carolina Björkas, Antti Tolvanen, Katharina Vörtler, Tommi Järvi Group Räsänen: Senior scientist Leonid Khriachtchev. Post-docs Sebastian Hasenstab-Riedel (Lynen/Humboldt fellow), Antti Lignell. Graduate students Karoliina Honkala, Kseniya Marushkevich. Group Vaara: Post-doc Michal Straka, graduate students Matti Hanni, Teemu O. Pennanen, Teemu S. Pennanen.
Running time 2006-2011. Chairman 2006-08 Pekka Pyykkö, chairman 2009-11 Lauri Halonen. Vice-chairman Kai Nordlund. Coordinator Dage Sundholm. Budget 2007: Academy of Finland 392 060 euro. University of Helsinki 167 000. Output 2006: 60 papers, 9 FM, 3 FT. 2007: 77 papers, 8 FM, 4 FT. Some numerical data
Some long-term activities of P. Pyykkö Relativistic effects since 1970, first on hyperfine effects, then on chemical bonding. Later QED: The earlier work was ’101% right’. The chemical differences between Rows 5/6 (Ag/Au) predominantly relativistic. Chem. Rev. 1988. ’Metallophilic attraction’ since 1991. Strong dispersion effect, ’strongest vdW in the World’. Au(I)...Au(I). CR 1997. Prediction of new molecules, 1977- now. Simple understanding of chemical bonding.
Au72 • Predicted in 2008 [1]. Stabilized by relativity, 72-electron aromaticity (s+p+d+f+g+h). Chiral, icosahedral, group I. Energetically more stable than Au20, for instance. • Not yet prepared. [1] A. J. Karttunen, M. Linnolahti, T.A. Pakkanen, P. Pyykkö, Chem. Comm. 465 (2008)
IR D. Sundholm: New explanation for how retinal works R. Send, D. Sundholm, J. Phys. Chem. A,111, 8766 (2007).
IR tunneling The Räsänen group: The first trans-cisformic acid dimer in solid argon trans-trans cis-FA in dimer #1 decays more slowly than cis-FA monomer! trans-cis K. Marushkevich et al.,J. Am. Chem. Soc.,128, 12060 (2006); material courtesy of L. Khriachtchev
The Räsänen group: The first trans-cis formic acid dimer • Different barrier heights (2676 cm1 for monomer and 3432 cm1 for dimer) explain the higher stability of the dimer. • The stability of the trans-cis dimer does not change with temperature, in contrast to the cis monomer. Why? K. Marushkevich et al.,J. Am. Chem. Soc.,128, 12060 (2006); material courtesy of L. Khriachtchev
The Räsänen group: Laser-controlled stress of Si nanocrystals in silica • Experiments with free-standing Si/SiO2 superlattice annealed at 1100 oC • HTA1: High-temperature laser annealing • increases Raman intensity by 100, • shifts the band up to 525 cm-1 • LTA: Low-temperature laser annealing shifts the band down to 516 cm-1 • HTA2: The band can be shifted back to 525 cm-1 by high-temperature laser annealing, and so on. 3 GPa HTA2 LTA HTA1 as-prepared x50 Khriachtchev et al. APL 88, 013102 (2006)
No stress No stress Stress Laser-controlled stress of Si nanocrystals in silica • First, Si-nc is unstressed (low Raman shift) • HTAmelts Si-nc and the silica surrounding relaxes (no stress at high temperature) • Temperature decreases, Si particle crystallizes and the volume increases (by 10%) • Si particle with volume VS inserted into a sphere with volume VMin a SiO2 matrix K - modulus of compression, G - shear modulus 3 GPa
Halonen group: Water dimer problem • Energy balance and greenhouse effects in Earth’s atmosphere: • Has the contribution of the water dimer been neglected? • Why has the water dimer not beenobserved in the atmosphere? • Ourresults indicate that the energy is absorbed in such a widewavelength range that the observation of water dimer becomesdifficult.
Computed energy absorption in a wavelength region where unsuccessful experimental attempts have been made Simple model Realistic model
Laser Breath Analysis Breath transferred to cell Helicobacter pylori Patient Cavity ringdown spectroscopy Diseases Diagnosis
Vaara group: Xe dissolved in Model Liquid Crystal NPT-Monte Carlo; 1610 particles interacting with theGay-Berne potential GB-Xe potential and Xe NMR response parametrised through B3LYP calculations of prototype atomistic mesogens J. Lintuvuori, M. Straka and J. Vaara, Phys. Rev. E 75, 031707 (2007)
Vaara group: 129Xe chemical shift inside cavity,Xe@C60 Systematic inclusion of different physical effects: relativity (BPPT), electron correlation (DFT), T-dependent dynamics with rigid (diatomic 3D) and flexible cage (BOMD) and solvent (PCM) M. Straka, P. Lantto, and J. Vaara, J. Phys. Chem. A, in press. • Correlation description (DFT functional) of NR shift most important • Relativity is about +10% => necessary to include! • Dynamical effect mainly due to thermal motion of the cage: ~ +10% (BOMD) • Still +26 ppm is missing: • partly due to missing explicit, static or dynamic, solvent effects • Most likely reason, however, is the imperfect DFT functional
Vaara group: Effect of local environment on NMR parameters in liquid water • B3LYP NMR parameter calculations for central molecules in clusters from liquid water NVE ensemble CPMD simulation • NMR parameters: shielding and NQCC for H/D and oxygen nuclei • NMR parameter averages for molecules in different local environments (different number of hydrogen bonds) • A detailed account of how local environmentaffects NMR parameters in liquid waterthe effect of broken/extra hydrogen bonds T. S. Pennanen, P. Lantto, A. J. Sillanpää, J. Vaara, J. Phys.Chem. A, 111, 182 (2007).
Theory of paramagnetic NMR • Expanded theory for nuclear magnetic resonance in open-shell systems (T.O. Pennanen & J. Vaara, accepted for publication in Phys. Rev. Lett.) • Implementation of theory using molecular properties available in current quantum chemical programs. • Calculations for metal-containing systems, e.g. boranes with possible nanomachine applications. (joint with D. Hnyk from Czech Academy of Sciences)
Nordlund group (Physics): fusion reactor materials • Nuclear fusion could provide nearly limitless energy to humanity – known fuel reserves exist for millions of years • The biggest remaining hurdle to develop a reliably energy-producing fusion power plant is the choice of materials for the reactor • Key problem: atoms and molecules which escape the 100 million degrees hot fusion plasma erode the reactor walls • But how this happens is not well understood! • We are studying this as partners in the EU fusion organization ITER fusion reactor, under construction
CHx and C2Hy erosion C-based reactor wall Nordlund group (Physics): fusion reactor materials • The worst erosion feature is thatany carbon-based material erodes • This was known for ~30 years • But the reason was not known • We have shown it is a previously unknown type of physico-chemical reaction occuring when the hot fusion H atoms interact with any C-based material • Understanding now guides ITER materials selection Incoming H atom Outgoing CH3 molecule [Nordlund et al, Pure and Applied Chemistry (2006)]
Nordlund group (Physics): nanoscience • Controlled manipulation of materials at the nanoscale holds great promise for the development of entirely new kinds of functionality in materials • Our atomistic simulations can treat entire nanoobjectsfully on an atomic level! Simulations of carbon nanotube-based materials has shown that their properties can be improved on with ion irradiation! Atomistic model of the Si nanocrystal made in the Räsänen group showed importance of interface defects [Djurabekova and Nordlund, Physical Review B 2008] [Krasheninnikov and Banhart, Nature Materials (2007)]