Peters, Laurens Dirk Marga (2020): Development and application of efficient ab initio molecular dynamics simulations of ground and excited states. Dissertation, LMU München: Faculty of Chemistry and Pharmacy 

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Abstract
Ab initio molecular dynamics reflect the movement of nuclei on a potential energy surface generated by ab initio methods. These simulations give access to an entire series of chemically relevant properties, such as vibrational spectra and free energies, and have thus become indispensable in, for example, biochemistry and materials sciences. They are, however, computationally demanding, due to the expensive quantumchemical calculations that are required at every step. In order to overcome some of the limitations, this thesis presents steps towards efficient but still accurate \textit{ab initio} molecular dynamics simulations, combining recent progress in different fields of computational chemistry. The timeconsuming twoelectron integral evaluations are conducted on graphics processing units. Their massively parallel architecture leads to speedups (with respect to calculations on central processing units) and strong scaling is observed. Expensive electronic structure calculations are circumvented using parametrized methods, such as the corrected small basis set HartreeFock method or simplified timedependent density functional theory. From the field of molecular dynamics, the extended Lagrangian method is adopted to stabilize the trajectories and to accelerate the convergence of the selfconsistent field algorithm. Finally, couplings between electronic states are approximated from a finite differences approach to avoid the timeconsuming analytical evaluations at the timedependent density functional theory level. As a result of these approaches, large molecular systems become accessible at comparably low computational cost. This is demonstrated for several illustrative applications. Excitedstate dynamics are used to explore the relaxation pathway of the rhodopsin protein and four newly designed rotary molecular motors using the same Schiff base motif. Groundstate simulations deliver vibrational spectra of mediumsized molecules and liquid water. They are used in addition to determine free energy differences of molecular transformations, for which a novel scheme is introduced delivering deeper insights into the underlying process.
Item Type:  Theses (Dissertation, LMU Munich) 

Subjects:  500 Natural sciences and mathematics 500 Natural sciences and mathematics > 540 Chemistry and allied sciences 
Faculties:  Faculty of Chemistry and Pharmacy 
Language:  English 
Date of oral examination:  12. February 2020 
1. Referee:  Ochsenfeld, Christian 
MD5 Checksum of the PDFfile:  b6d6deca3f1e2a6ed312319afbdf09c9 
Signature of the printed copy:  0001/UMC 27055 
ID Code:  25938 
Deposited On:  29. Apr 2020 14:33 
Last Modified:  23. Oct 2020 14:08 