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SFF-Sentre for fremragende forskn

Centre for Theoretical and Computational Chemistry, CTCC

Alternative title: CTCC Senter for teoretisk og beregningsbasert kjemi

Awarded: NOK 93.9 mill.

Chemistry is traditionally an experimental science. However, during the last decades, a new approach has become important: computer simulations. At the most fundamental level, chemical systems are simulated by solving the Schrödinger equation (or the corresponding relativistic Dirac equation) for the electrons and nuclei that make up molecules of interest. Such simulations are complicated since even small molecules consist of many particles interacting with one another. Quantum mechanical simulations of chemical systems have therefore only become a useful tool with the emergence of powerful computers. At the Centre for Theoretical and Computational Chemistry, we have developed new methods for quantum-mechanical simulations of chemical systems and processes. These methods have made it possible to discover new phenomena and explain known phenomena in chemistry, physics and biology. We give four examples. A fundamental concept in chemistry is chemical bonding. In textbooks, two types bonds are distinguished: ionic bonding (where electrons are transferred between the atoms) and covalent bonding (where electrons are shared between the atoms). In 2012, we demonstrated the existence of new bonding mechanism for molecules in extreme magnetic fields. As two atoms approach each other, the rotational energy of the electrons in the field is (under certain conditions) lowered, thereby binding the atoms together. In this manner, rare gas atoms (which normally do form bonds) form stable molecules! Since this magnetic bonding occurs only in extreme magnetic fields (encountered in the atmosphere of magnetic white dwarf stars), it has not been discovered earlier. Intriguingly, the magnetic bonding is not only of astrophysical interest - it probably exists also in certain crystals under Earth-like conditions. Human vision occurs as particles of light (photons) enter the eye and transfer their energy to the retinal molecule. The energy absorbed by retinal generates a nerve signal that is transmitted to the brain. However, the eye can detect only photons of a certain energy. If the photons have too little or too much energy, they cannot be absorbed and will not generate a nerve signal. Infrared photons, in particular, have too little energy to generate a nerve signal. Nevertheless, human beings can, under certain conditions, detect infrared light (seen as green). In an article published in 2014, we explained this phenomenon. If two infrared photons hit the same retinal molecule at the same time, they can be absorbed simultaneously, transmitting the same amount of energy and generating the same signal as single visible photon. For this to happen, the infrared light must be intense so that many photons enter the eye at any given time, increasing the probability that each retinal molecule is hit by two photons simultaneously. Electrons in atoms and molecules are fast. In fact, in atoms of sufficiently high nuclear charge such as gold and mercury, the electron move close to the speed of light. To describe such atoms, we must therefore use relativistic rather than nonrelativistic quantum mechanics - if not, gold becomes silvery and mercury becomes solid. However, even though the importance of relativity in chemistry has been recognized for decades, its importance for biological processes has not been appreciated. In 2016, we demonstrated how certain enzymatic processes are incorrectly described at the nonrelativistic level. In particular, we showed that the methylation of cobalt corrinoids occurs in a single step, not in several steps as predicted nonrelativistically. Surprisingly, therefore, even the processes of life cannot be correctly described without using Einstein's theory of relativity. Enzymes catalyse chemical processes of all living organisms. Without enzymes, many processes would not proceed sufficiently fast to support life. However, like all chemical processes, enzymatic processes are strongly temperature dependent - they are much faster at high temperature than at low temperatures. Many organisms exist in cold environments - for example, fish in near-freezing waters. For a long time, it has been a mystery how enzymatic processes can proceed sufficiently fast at such temperatures. In 2016, we solved this puzzle. Cold adaption of enzymatic processes does not occur (as one would naively expect) at the active site inside the enzyme. Instead, it occurs on the surface of the enzyme, which is in cold-adapted enzymes is softer than in other enzymes, in a subtle manner leading to an acceleration of the enzymatic process. This insight is crucial for further progress in the field - for example, towards enzymatic control.

The CTCC will lead a broad, concerted effort in the field of computational chemistry, creating strong links between experimental and theoretical chemistry. The CTCC has three pillars that all are central to the success of the centre: Development, applica tion and education. The key focus area for the methodological advances to be made at the CTCC will be the development of theories and computer programs for the calculation of molecular energies and properties. The aim is to develop a unified computation al approach to molecules, liquids and solids. This goal will be pursued along to different, yet complementary approaches, namely linear-scaling methods to curb the cost of traditional quantum-chemistry methods, and multiscale models to accurately and effi ciently partition a problem into regions of different chemical importance (and thus computational accuracy). The application of computational modeling tools will in the CTCC focus on several important areas of modern chemical research of particular impo rtance to Norwegian science and industry. More specifically, the CTCC will focus on the following application areas: (1) spectroscopy in a wide frequency range, (2) solid-state chemistry and materials science, (3) heterogeneous catalysis, (4) biological c hemistry, (5) medicinal chemistry, and (6) environmental science. The CTCC will establish a dissemination and education program for bringing the latest technology of computational chemistry to the entire Norwegian research community. To this end, trainin g courses will be set up. We will also have an active affiliation program directed at all computational and theoretical chemists in Norway. The CTCC will make a special effort to encourage young female researcher to enter science and put them in a posit ion to better compete for faculty positions. In this manner, CTCC will be an important instrument for increasing the number of female faculty members in physical chemistry in Norway.

Publications from Cristin

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SFF-Sentre for fremragende forskn