Back to search

SFF-Sentre for fremragende forskn

Hylleraas Centre for Quantum Molecular Sciences

Alternative title: Hylleraas-senteret

Awarded: NOK 146.0 mill.

Today, huge resources are being invested in new experimental facilities for studying molecules and materials such as the MAX IV Laboratory and the European XFEL. Increasingly complex systems are being studied at increasingly high resolution by embedding them in ultra-fast and ultra-intense photon environments. The opportunities generated by these developments are enormous. However, without advanced computation as a guide, experimental observations may be misinterpreted, discoveries missed, and opportunities lost. The Hylleraas Centre aims to develop, apply, and distribute tools to simulate the complex systems and to interpret these new observations - advancing a revolution in computation to match that of experiment in chemistry, physics, and biology. Today, it is easy to describe small molecules in weak fields, interacting with one or two photons - the difficulty is to extend this description to hundreds, thousands, and even millions of atoms in strong fields, interacting with multiple photons. To achieve this, processes that occur locally and globally, over short and long time scales, often in competition, must be described in a balanced manner, rigorously based on the laws of quantum mechanics - all at high accuracy and low cost. The tool for such studies are multiscale methods. At the Hylleraas Centre, we develop and apply multiscale methods with emphasis on the interaction of matter with external fields and radiation. With these tools, we will not only be able study the new spectroscopic processes but also the exotic chemistry of molecules in the fierce environments of many stellar objects. During the last year, we have developed the first methods for simulating the dynamics of molecules in a magnetic field and used these methods to calculate the microwave and infrared spectra of molecules in strong magnetic fields. These spectra turn out to have a very different structure from the corresponding spectra of molecules on Earth and give a fascinating insight into the chemistry of molecules in strong magnetic fields. Such calculated spectra are needed if we are to detect molecules in the atmospheres of magnetic white dwarfs. Regarding spectroscopic methods under normal conditions, we have recently developed new methods for the study of X-ray absorption spectra. Because of the high velocity of electrons affected by the X-rays, an accurate description of such processes requires a relativistic treatment of the electrons. This can be achieved in different ways ? typically by correcting the nonrelativistic treatment in different ways. However, the most reliable (but also most expensive) approach is to solve the relativistic Dirac equation for the electrons, rather than to correct the solution to the nonrelativistic Schrödinger equation. We have extensive experience with solving the relativistic Dirac equation ? most recently, in connection with studies of nuclear magnetic resonance spectroscopy, the principle behind magnetic resonance imaging (MR). During the last year, we have extended the relativistic treatment to X-ray spectroscopy and shown that it gives a more accurate treatment than other methods, without the use of empirical parameters. Our approach and implementation are sufficiently efficient to be applied to molecules containing up to one hundred atoms. At present, the Hylleraas Centre is also developing more advanced methods for atoms and molecules in intense laser pulses. Nearly always in quantum chemistry, we describe the ?slow? nuclei and the ?fast? electrons in different ways, within the Born?Oppenheimer approximation. In a laser pulse, the events are so fast and so dramatic that this approach may not be sufficient. We are therefore exploring methods beyond the Born?Oppenheimer approximation, solving the Schrödinger equation simultaneously for all particles. For the time being, we concentrate on small atoms and molecules ? in the future, these methods must be simplified to treat larger systems.

The Hylleraas Centre for Quantum Molecular Sciences will make a decisive, timely contribution to the chemistry, physics and biology of molecules by developing an integrated multiscale approach for complex systems, emphasising matter-field interactions. The emergence of advanced laser technology and fourth-generation light sources creates new opportunities and challenges that require major advances in the modelling of complex systems in extreme environments. The Hylleraas Centre will meet this challenge by developing novel computational methods that will allow us to treat systems containing thousands and even millions of atoms, by unravelling their response to short laser pulses and strong fields, and by exploring processes extending from attoseconds to microseconds. The Hylleraas Centre gathers world-leading expertise in the domains of electronic-structure theory, multiscale modelling, computational spectroscopy, and the use of computation to understand and control complex chemical and biological systems. The centre is uniquely positioned to take the lead in the modelling and understanding of the new scientific frontiers that will be enabled by new experimental facilities. Through an extensive incoming sabbatical programme, a generous visitors programme, focus bienniums, international workshops, conferences, outreach activities and seminar series, the Hylleraas Centre will create an internationally visible and attractive centre for the computational modelling and understanding of new chemistry at the frontiers of a wide range of scientific disciplines. Through the training of PhD students and postdocs, the establishment of national courses in theoretical chemistry and international winter schools, the Hylleraas Centre will educate a new generation of computational scientists skilled to address the new research frontiers. The centre will continue the PIs' longstanding efforts to improve gender balance in theoretical and computational chemistry.

Activity:

SFF-Sentre for fremragende forskn