Title: Development of formalisms based on locally coupled open subsystems for calculations in molecular electronic structure and dynamics

Abstract

Quantum embedding theories model a collection of interacting molecules as a set of subsystems, where each can be treated with a particular electronic structure method (wave function or density functional theory, for example); these theories can lead to computationally efficient and accurate algorithms. Motivated by challenges in the field, we previously described a formalism (that models two subsystems), which we call “locally coupled open subsystems” (LCOS), for the computation of ground-state energies, fractional electron-occupation numbers of the subsystems, and the size-consistent limit of subsystem dissociation. In this work we present the full (nonrelativistic) LCOS theory and the following extensions of our previous work: (i) the framework to study systems composed of multiple subsystems and a procedure to spin-adapt the auxiliary wave function that describes the partitioned system, so that its spin state matches that of the real system of interest; (ii) potential functionals and ideas to employ machine learning for the computation of ground-state densities and energies; (iii) formulation of two LCOS ground-state approaches where the fragments are assigned Kohn-Sham wave functions; and (iv) a time-dependent (TD) extension of these two ground-state formalisms in which the state of the subsystems evolves according to a unitary propagation; from this evolution wemore » can extract TD electron populations of the fragments, for instance. We also discuss potential applications of the TD LCOS theory to linear photoabsorption and Raman spectroscopy. As a result, the developments presented in this work can lead to ground-state and TD electronic structure calculations where the computational scaling can be controlled, depending on the level of theory and the accuracy desired to model each one of the subsystems and their coupling.« less

Authors:

Mosquera, Martín A. ^[1]; Jones, Leighton O. ^[1]; Ratner, Mark A. ^[1]; Schatz, George C. ^[1]

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+ Show Author Affiliations

1. Northwestern Univ., Evanston, IL (United States)

Publication Date:

Wed Dec 05 00:00:00 EST 2018

Research Org.:

Northwestern Univ., Evanston, IL (United States)

Sponsoring Org.:

USDOE Office of Science (SC)

OSTI Identifier:

1610752

Alternate Identifier(s):

OSTI ID: 1484548

Grant/Contract Number:  

SC0004752

Resource Type:

Accepted Manuscript

Journal Name:

Physical Review A

Additional Journal Information:

Journal Volume: 98; Journal Issue: 6; Journal ID: ISSN 2469-9926

Publisher:

American Physical Society (APS)

Country of Publication:

United States

Language:

English

Subject:

74 ATOMIC AND MOLECULAR PHYSICS; Optics; Physics; Machine learning; Strongly correlated systems; Density functional theory; Time-dependent DFT