Trial lecture
November 29th, 10:15 AM, Auditorium 3, Kjemibygningen
"Quantum chemical calculation of molecular properties"
Conferral summary
Doktorgradsavhandlingens hovedmål var å redusere kostnadene av kvantemekaniske beregninger av molekylers magnetiske egenskaper med nye tilnærmingsmetoder. For molekyler med noen hundretalls atomer kan vi nå beregne atomers skjermingskonstanter (av betydning for kjernemagnetisk resonans) en størrelsesorden raskere enn tidligere. Ved beregninger har vi også vist at elektronstrømmer indusert av et magnetfelt er et godt kriterium for aromatisitet i molekyler.
Computational speed-up to study magnetic and electric properties of large molecules
For gaining new insights in chemistry, a balance between experiment and theory is essential. For example, molecular electronic structures and properties can be calculated using accurate quantum chemical methods. A drawback is that these calculations become quite expensive with an increase in the size of the molecule, restricting possible applications.
This PhD thesis is dedicated to overcome this key problem aiming at reducing computational cost without compromising the accuracy of the results by using modern approximation methods.
The work covers the calculation of molecular properties like nuclear magnetic shielding, electric dipole polarizability and vertical excitation energies. As a result, speed-ups by almost an order of magnitude have been achieved, making it possible to study comparatively large molecules in less time.
Another part of the thesis is dedicated to molecular aromaticity, which belongs to the oldest concepts in chemistry. As a result, it was shown that magnetic and energetic criteria are linearly related to each other. Therefore, the aromaticity studies based on magnetically induced current densities are a reliable approach for assessing the aromatic character of a molecule.
