Complexity Reduction in Large Quantum Systems: Fragment Identification and Population Analysis via a Local Optimized Minimal Basis
We present, within KohnSham Density Functional Theory calculations, a quantitative method to identify and assess the partitioning of a large quantum mechanical system into fragments. We then introduce a simple and efficient formalism (which can be written as generalization of other wellknown population analyses) to extract, from first principles, electrostatic multipoles for these fragments. The corresponding fragment multipoles can in this way be seen as reliable (pseudo) observables. By applying our formalism within the code BigDFT, we show that the usage of a minimal set of insitu optimized basis functions is of utmost importance for having at the same time a proper fragment definition and an accurate description of the electronic structure. With this approach it becomes possible to simplify the modeling of environmental fragments by a set of multipoles, without notable loss of precision in the description of the active quantum mechanical region. Furthermore, this leads to a considerable reduction of the degrees of freedom by an effective coarsegraining approach, eventually also paving the way towards efficient QM/QM and QM/MM methods coupling together different levels of accuracy.
 Authors:

^{[1]}
;
^{[2]};
^{[3]};
^{[4]}
 Barcelona Supercomputing Center (BSC), Barcelona (Spain)
 Institut de Biologie et de Technologie de Saclay, GifsurYvette Cedex (France)
 Argonne National Lab. (ANL), Argonne, IL (United States)
 Univ. Grenoble Alpes, Grenoble (France); CEA, Grenoble (France)
 Publication Date:
 Grant/Contract Number:
 AC0206CH11357
 Type:
 Accepted Manuscript
 Journal Name:
 Journal of Chemical Theory and Computation
 Additional Journal Information:
 Journal Volume: 13; Journal Issue: 9; Journal ID: ISSN 15499618
 Publisher:
 American Chemical Society
 Research Org:
 Argonne National Lab. (ANL), Argonne, IL (United States)
 Sponsoring Org:
 European Commission, Community Research and Development Information Service (CORDIS), EXTended Model of Organic Semiconductors (ExtMOS); Energy Oriented Centre of Excellence (EoCoE); USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC22); Argonne National Laboratory, Argonne Leadership Computing Facility; MaX Centre of Excellence
 Country of Publication:
 United States
 Language:
 English
 Subject:
 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
 OSTI Identifier:
 1400406
Mohr, Stephan, Masella, Michel, Ratcliff, Laura E., and Genovese, Luigi. Complexity Reduction in Large Quantum Systems: Fragment Identification and Population Analysis via a Local Optimized Minimal Basis. United States: N. p.,
Web. doi:10.1021/acs.jctc.7b00291.
Mohr, Stephan, Masella, Michel, Ratcliff, Laura E., & Genovese, Luigi. Complexity Reduction in Large Quantum Systems: Fragment Identification and Population Analysis via a Local Optimized Minimal Basis. United States. doi:10.1021/acs.jctc.7b00291.
Mohr, Stephan, Masella, Michel, Ratcliff, Laura E., and Genovese, Luigi. 2017.
"Complexity Reduction in Large Quantum Systems: Fragment Identification and Population Analysis via a Local Optimized Minimal Basis". United States.
doi:10.1021/acs.jctc.7b00291. https://www.osti.gov/servlets/purl/1400406.
@article{osti_1400406,
title = {Complexity Reduction in Large Quantum Systems: Fragment Identification and Population Analysis via a Local Optimized Minimal Basis},
author = {Mohr, Stephan and Masella, Michel and Ratcliff, Laura E. and Genovese, Luigi},
abstractNote = {We present, within KohnSham Density Functional Theory calculations, a quantitative method to identify and assess the partitioning of a large quantum mechanical system into fragments. We then introduce a simple and efficient formalism (which can be written as generalization of other wellknown population analyses) to extract, from first principles, electrostatic multipoles for these fragments. The corresponding fragment multipoles can in this way be seen as reliable (pseudo) observables. By applying our formalism within the code BigDFT, we show that the usage of a minimal set of insitu optimized basis functions is of utmost importance for having at the same time a proper fragment definition and an accurate description of the electronic structure. With this approach it becomes possible to simplify the modeling of environmental fragments by a set of multipoles, without notable loss of precision in the description of the active quantum mechanical region. Furthermore, this leads to a considerable reduction of the degrees of freedom by an effective coarsegraining approach, eventually also paving the way towards efficient QM/QM and QM/MM methods coupling together different levels of accuracy.},
doi = {10.1021/acs.jctc.7b00291},
journal = {Journal of Chemical Theory and Computation},
number = 9,
volume = 13,
place = {United States},
year = {2017},
month = {7}
}