Presentation on theme: "Finnish CoE of Computational Molecular Science Laskennallisen molekyylitutkimuksen huippuyksikkö Spetsenheten för datorstödd molekylforskning Kanslerin."— Presentation transcript:
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. Entire UoH: 38000 students. 8 national CoE:s, including ’Finnish Centre of Excellence of Computational Molecular Science’ (2006-2011). (CMS) CMS groups: Pyykkö-Sundholm, Halonen, Räsänen, Vaara, Nordlund. About 60 people. Nordic ’umbrella’ of CoE:s. The Kumpula Campus, University of Helsinki, Finland
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.
Predicted in 2008 . Stabilized by relativity, 72-electron aromaticity (s+p+d+f+g+h). Chiral, icosahedral, group I. Energetically more stable than Au 20, for instance. Not yet prepared.  A. J. Karttunen, M. Linnolahti, T.A. Pakkanen, P. Pyykkö, Chem. Comm. 465 (2008) Au 72
D. Sundholm: New explanation for how retinal works R. Send, D. Sundholm, J. Phys. Chem. A, 111, 8766 (2007). IR
The Räsänen group: The first trans-cis formic acid dimer in solid argon K. Marushkevich et al., J. Am. Chem. Soc., 128, 12060 (2006); material courtesy of L. Khriachtchev trans-trans IR tunneling trans-cis cis-FA in dimer #1 decays more slowly than cis-FA monomer!
Different barrier heights (2676 cm 1 for monomer and 3432 cm 1 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: The first trans-cis formic acid dimer
Experiments with free-standing Si/SiO 2 superlattice annealed at 1100 o C 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. The Räsänen group: Laser-controlled stress of Si nanocrystals in silica Khriachtchev et al. APL 88, 013102 (2006) HTA2 LTA HTA1 as-prepared x50 3 GPa
Laser-controlled stress of Si nanocrystals in silica First, Si-nc is unstressed (low Raman shift) HTA melts 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 V S inserted into a sphere with volume V M in a SiO 2 matrix K - modulus of compression, G - shear modulus No stress Stress 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 been observed in the atmosphere? Our results indicate that the energy is absorbed in such a wide wavelength range that the observation of water dimer becomes difficult.
Simple model Realistic model Computed energy absorption in a wavelength region where unsuccessful experimental attempts have been made
NPT-Monte Carlo; 1610 particles interacting with the Gay-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: Xe dissolved in Model Liquid Crystal
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) 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 M. Straka, P. Lantto, and J. Vaara, J. Phys. Chem. A, in press.
Vaara group: Effect of local environment on NMR parameters in liquid water T. S. Pennanen, P. Lantto, A. J. Sillanpää, J. Vaara, J. Phys. Chem. A, 111, 182 (2007). A detailed account of how local environment affects NMR parameters in liquid water the effect of broken/extra hydrogen bonds 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)
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) Theory of paramagnetic NMR
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
Nordlund group (Physics): fusion reactor materials The worst erosion feature is that any 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 CH x and C 2 H y erosion C-based reactor wall 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 nanoobjects fully on an atomic level! Atomistic model of the Si nanocrystal made in the Räsänen group showed importance of interface defects [Djurabekova and Nordlund, Physical Review B 2008] Simulations of carbon nanotube-based materials has shown that their properties can be improved on with ion irradiation! [Krasheninnikov and Banhart, Nature Materials (2007)]
Nordlund group (Physics): structures of ice and water