Embedding theory for excited states

Khait, Yuriy G.; Hoffmann, Mark R.

doi:10.1063/1.3460594

Cited by 55 publications

(66 citation statements)

References 21 publications

(18 reference statements)

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“…Following the Levy-Perdew theorem, 4 other than the lowest energy solutions of the Euler-Lagrange equation of FDET can be associated with excited states as noticed by Khait and Hoffmann. 5 Without further approximations concerning the FDET embedding potential, FDET based methods feature a qualitative difference from most of other embedding methods used in practice -the FDET embedding potential depends on the embedded density (ρ A (⃗ r)). This leads to the following practical consequences.…”

Section: Introductionmentioning

confidence: 99%

Orthogonality of embedded wave functions for different states in frozen-density embedding theory

Zech

Aquilante

Wesołowski

2015

The Journal of Chemical Physics

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Other than lowest-energy stationary embedded wave functions obtained in Frozen-Density Embedding Theory (FDET) [T. A. Wesolowski, Phys. Rev. A 77, 012504 (2008)] can be associated with electronic excited states but they can be mutually non-orthogonal. Although this does not violate any physical principles -embedded wave functions are only auxiliary objects used to obtain stationary densities -working with orthogonal functions has many practical advantages. In the present work, we show numerically that excitation energies obtained using conventional FDET calculations (allowing for non-orthogonality) can be obtained using embedded wave functions which are strictly orthogonal. The used method preserves the mathematical structure of FDET and self-consistency between energy, embedded wave function, and the embedding potential (they are connected through the Euler-Lagrange equations). The orthogonality is built-in through the linearization in the embedded density of the relevant components of the total energy functional. Moreover, we show formally that the differences between the expectation values of the embedded Hamiltonian are equal to the excitation energies, which is the exact result within linearized FDET. Linearized FDET is shown to be a robust approximation for a large class of reference densities. C 2015 AIP Publishing LLC. [http://dx

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Section: Introductionmentioning

confidence: 99%

Orthogonality of embedded wave functions for different states in frozen-density embedding theory

Zech

Aquilante

Wesołowski

2015

The Journal of Chemical Physics

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“…In particular, WFT-in-DFT embedding utilizes the theoretical framework of DFT embedding to enable the WFT description of a given subsystem in the effective potential that is created by the remaining electronic density of the system. [16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] We recently introduced a simple, projection-based method for performing accurate WFT-in-DFT embedding calculations 30 that avoids the need for a numerically challenging optimized effective potential (OEP) calculation 24,25,[31][32][33][34] via the introduction of a level-shift operator. It was shown that this method enables the accurate calculation of WFT-in-DFT subsystem correlation energies, as well as many-body expansions (MBEs) of the total WFT correlation energy.…”

Section: Introductionmentioning

confidence: 99%

“…Among these are the QM/MM, [1][2][3][4][5][6] ONIOM, 7,8 fragment molecular orbital (FMO), [9][10][11][12][13][14][15] and wavefunction theory (WFT)-in-density functional theory (DFT) embedding [16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] approaches, which allow for the treatment of systems that would not be practical using conventional WFT approaches. In particular, WFT-in-DFT embedding utilizes the theoretical framework of DFT embedding to enable the WFT description of a given subsystem in the effective potential that is created by the remaining electronic density of the system.…”

Section: Introductionmentioning

confidence: 99%

Accurate basis set truncation for wavefunction embedding

Barnes

Goodpaster

Manby³

et al. 2013

The Journal of Chemical Physics

127

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Density functional theory (DFT) provides a formally exact framework for performing embedded subsystem electronic structure calculations, including DFT-in-DFT and wavefunction theory-in-DFT descriptions. In the interest of efficiency, it is desirable to truncate the atomic orbital basis set in which the subsystem calculation is performed, thus avoiding high-order scaling with respect to the size of the MO virtual space. In this study, we extend a recently introduced projection-based embedding method [F. R. Manby, M. Stella, J. D. Goodpaster, and T. F. Miller III, J. Chem. Theory Comput. 8, 2564 (2012)] to allow for the systematic and accurate truncation of the embedded subsystem basis set. The approach is applied to both covalently and non-covalently bound test cases, including water clusters and polypeptide chains, and it is demonstrated that errors associated with basis set truncation are controllable to well within chemical accuracy. Furthermore, we show that this approach allows for switching between accurate projection-based embedding and DFT embedding with approximate kinetic energy (KE) functionals; in this sense, the approach provides a means of systematically improving upon the use of approximate KE functionals in DFT embedding. © 2013 AIP Publishing LLC. [http://dx

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“…[25][26][27][28] It can be shown that using such an embedding potentials is formally exact (i.e., it is exact if the exact exchangecorrelation and kinetic-energy functionals are used and the limit of an exact WFT description is reached). 65,66 In ref. 33, three of us proposed a simplified scheme for the calculation of local excitation energies with WFT-in-DFT embedding.…”

Section: Wft-in-dft Embeddingmentioning

confidence: 99%

PyADF — A scripting framework for multiscale quantum chemistry

Jacob

Beyhan²,

Bulo³

et al. 2011

J Comput Chem

100

106

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Abstract:Applications of quantum chemistry have evolved from single or a few calculations to more complicated workflows, in which a series of interrelated computational tasks is performed. In particular multiscale simulations, which combine different levels of accuracy, typically require a large number of individual calculations that depend on each other. Consequently, there is a need to automate such workflows. For this purpose we have developed PyAdf, a scripting framework for quantum chemistry. PyAdf handles all steps necessary in a typical workflow in quantum chemistry and is easily extensible due to its object-oriented implementation in the Python programming language. We give an overview of the capabilities of PyAdf and illustrate its usefulness in quantum-chemical multiscale simulations with a number of examples taken from recent applications.

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Embedding theory for excited states

Cited by 55 publications

References 21 publications

Orthogonality of embedded wave functions for different states in frozen-density embedding theory

Orthogonality of embedded wave functions for different states in frozen-density embedding theory

Accurate basis set truncation for wavefunction embedding

PyADF — A scripting framework for multiscale quantum chemistry

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