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Embedding‐theory‐based simulations using experimental electron densities for the environment
Author(s) -
Ricardi Niccolò,
Ernst Michelle,
Macchi Piero,
Wesolowski Tomasz Adam
Publication year - 2020
Publication title -
acta crystallographica section a
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.742
H-Index - 83
ISSN - 2053-2733
DOI - 10.1107/s2053273320008062
Subject(s) - density functional theory , embedding , wave function , electron , atomic physics , time dependent density functional theory , physics , excitation , space (punctuation) , electron density , molecular physics , crystallography , quantum mechanics , chemistry , computer science , artificial intelligence , operating system
The basic idea of frozen‐density embedding theory (FDET) is the constrained minimization of the Hohenberg–Kohn density functional E HK [ρ] performed using the auxiliary functional , where Ψ A is the embedded N A ‐electron wavefunction and ρ B ( r ) is a non‐negative function in real space integrating to a given number of electrons N B . This choice of independent variables in the total energy functional makes it possible to treat the corresponding two components of the total density using different methods in multi‐level simulations. The application of FDET using ρ B ( r ) reconstructed from X‐ray diffraction data for a molecular crystal is demonstrated for the first time. For eight hydrogen‐bonded clusters involving a chromophore (represented as Ψ A ) and the glycylglycine molecule [represented as ρ B ( r )], FDET is used to derive excitation energies. It is shown that experimental densities are suitable for use as ρ B ( r ) in FDET‐based simulations.