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FRINATEK-Fri prosj.st. mat.,naturv.,tek

Theoretical probing of local and ultrafast phenomena using advanced light sources

Alternative title: Teoretiske undersøkelser av lokale og ultrahurtige fenomener med avanserte lyskilder

Awarded: NOK 13.6 mill.

In the TheoLight project, we will extend the application range of coupled cluster theory as a method to describe the ultrafast coupled motion of nuclei and electrons in chemical systems. Nuclear dynamics will be described using ab initio methods, with varying accuracy in time together with rare event path sampling techniques. We will take initial steps toward developing highly accurate electron dynamics techniques based on the time-dependent coupled cluster equations. For the local spectroscopic methods, we will use multiscale modeling to enable accurate calculations on more complex molecular systems, such as biomolecules, non-trivial surfaces, and solvated systems. In addition, spectroscopic properties for high-level methods, carefully connected to lower-level wave function theories, will be developed, and we will use a coupling to molecular mechanics and continuum models to account for environmental effects. So far, we have made significant progress in developing multilevel methods and the nonadiabatic coupled cluster model is also well underway. We have carried out several projects with international collaborators and we foresee several more in the next period. We have recently completed the implementation of molecular gradients and nonadiabatic coupling elements necessary for dynamics calculations. Furthermore, the multilevel methods have been extended to CCSD/CC3 and we are currently applying the new code to the calculation of NEXAFS spectra of ammonium in water. The CC3 code has been further optimized and is now the fastests implementation available. We have furthermore developed methods to explicitly consider photons and their interaction with molecules. This has led to several publications in high-impact journals.

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In this project, we will enable and extend the applicability range of coupled cluster theory to the description of ultrafast and coupled nuclear-electron dynamics. Nuclear dynamics will be described at the ab initio level, and also a temporal multilevel aspect will be brought in by using rare event path sampling techniques. Further, we will take the intial steps in developing electron dynamics coupled cluster methods via time-dependent equations. For the local spectroscopic methods we will employ multiscale modelling to enable accurate calculations on more complex molecular systems such as biomolecules, non-trivial surfaces and solvated systems. Spectroscopic properties for high-level methods carefully connected to lower level wave function theories will be developed, and a coupling to molecular mechanics and continuum models will be employed to be able to account for environment effects.

Publications from Cristin

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Funding scheme:

FRINATEK-Fri prosj.st. mat.,naturv.,tek