Schurkus, Henry F. (2017): Highly Accurate Random Phase Approximation Methods With Linear Time Complexity. Dissertation, LMU München: Faculty of Chemistry and Pharmacy 

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Abstract
One of the key challenges of electronic structure theory is to find formulations to compute electronic groundstate energies with high accuracy while being applicable to a wide range of chemical problems. For systems beyond the few atom scale often computations achieving higher accuracies than the so called doublehybrid density functional approximations become prohibitively expensive. Here, the random phase approximation, which is known to yield such higher accuracy results has been developed from a theory applicable only to molecules on the tens of atoms scale into a highly accurate and widely applicable theory. To this end, a mathematical understanding has been developed that, without changing the computational complexity, allows to eliminate the error introduced by the resolutionoftheidentity approximation which had been introduced in the previous formulation. Furthermore, in this work a new formulation of the random phase approximation for molecules has been presented which achieves linearscaling of compute time with molecular size  thereby expanding the realm of molecules that can be treated on this level of theory to up to a thousand atoms on a simple desktop computer. Finally, the theory has been matured to allow for use of even extensive basis sets without drastically increasing runtimes. Overall, the presented theory is at least as accurate and even faster than the original formulation for all molecules for which compute time is significant and opens new possibilities for the highly accurate description of large quantum chemical systems.
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:  31. July 2017 
1. Referee:  Ochsenfeld, Christian 
MD5 Checksum of the PDFfile:  61d8fffc584217e381f0df36773c5ceb 
Signature of the printed copy:  0001/UMC 24869 
ID Code:  21059 
Deposited On:  09. Aug 2017 12:36 
Last Modified:  23. Oct 2020 18:54 