Active Learning Configuration Interaction for Excited-State Calculations of Polycyclic Aromatic Hydrocarbons

We present the active learning configuration interaction (ALCI) method for multiconfigurational calculations based on large active spaces. ALCI leverages the use of an active learning procedure to find important electronic configurations among the full configurational space generated within an activ...

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Bibliographic Details
Published in:Journal of chemical theory and computation 2021-12, Vol.17 (12), p.7518-7530
Main Authors: Jeong, WooSeok, Gaggioli, Carlo Alberto, Gagliardi, Laura
Format: Article
Language:English
Subjects:
Active learning
Algorithms
Configuration interaction
Density functional theory
Electrons
Excitation
Machine learning
Mathematical analysis
Orbitals
Perturbation theory
Polycyclic aromatic hydrocarbons
Quantum Electronic Structure
Wave functions
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Summary:We present the active learning configuration interaction (ALCI) method for multiconfigurational calculations based on large active spaces. ALCI leverages the use of an active learning procedure to find important electronic configurations among the full configurational space generated within an active space. We tested it for the calculation of singlet–singlet excited states of acenes and pyrene using different machine learning algorithms. The ALCI method yields excitation energies within 0.2–0.3 eV from those obtained by traditional complete active-space configuration interaction (CASCI) calculations (affordable for active spaces up to 16 electrons in 16 orbitals) by including only a small fraction of the CASCI configuration space in the calculations. For larger active spaces (we tested up to 26 electrons in 26 orbitals), not affordable with traditional CI methods, ALCI captures the trends of experimental excitation energies. Overall, ALCI provides satisfactory approximations to large active-space wave functions with up to 10 orders of magnitude fewer determinants for the systems presented here. These ALCI wave functions are promising and affordable starting points for the subsequent second-order perturbation theory or pair-density functional theory calculations.
ISSN:1549-9618
1549-9626
DOI:10.1021/acs.jctc.1c00769