Even-handed subsystem selection in projection-based embedding

Welborn, Matthew; Manby, Frederick R.; Miller, Thomas F.

doi:10.1063/1.5050533

Cited by 45 publications

(66 citation statements)

References 109 publications

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“…The Manby and Miller groups proposed the use of the parameter-dependent levelshift projection operator (hereinafter the µ operator) as 45,[60][61][62][63][64]…”

Section: Absolute Localization Projection-based Embeddingmentioning

confidence: 99%

Absolutely Localized Projection-Based Embedding for Excited States

Wen

Graham

Chulhai

et al. 2019

J. Chem. Theory Comput.

119

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We present a quantum embedding method that allows for the calculation of local excited states embedded in a Kohn-Sham density functional theory (DFT) environment. Projection-based quantum embedding methodologies provide a rigorous framework for performing DFT-in-DFT and wave function in DFT (WF-in-DFT) calculations. The use of absolute localization, where the density of each subsystem is expanded in only the basis functions associated with the atoms of that subsystem, provide improved computationally efficiency for WF-in-DFT calculations by reducing the number of orbitals in the WF calculation. In this work, we extend absolutely localized projection-based quantum embedding to study localized excited states using EOM-CCSD-in-DFT and TDDFT-in-DFT. The embedding results are highly accurate compared to the corresponding canonical EOM-CCSD and TDDFT results on the full system, with TDDFT-in-DFT frequently more accurate than canonical TDDFT. The 1 arXiv:1909.12423v1 [physics.chem-ph] 26 Sep 2019 absolute localization method is shown to eliminate the spurious low-lying excitation energies for charge transfer states and prevent over delocalization of excited states.Additionally, we attempt to recover the environment response caused by the electronic excitations in the high-level subsystem using different schemes and compare their accuracy. Finally, we apply this method to the calculation of the excited state energy of green fluorescent protein and show that we systematically converge to the full system results. Here we demonstrate how this method can be useful in understanding excited states, specifically which chemical moieties polarize to the excitation. This work shows absolutely localized projection-based quantum embedding can treat local electronic excitations accurately, and make computationally expensive WF methods applicable to systems beyond current computational limits. many systems. 16 However, the computational cost of EOM-CCSD (scaling as O(N 6 )) restricts its usage to about 50 or fewer atoms in a moderate basis. Methods that extend the applicability of EOM-CCSD to larger systems include the use of local orbitals, [17][18][19][20][21] restricted virtual spaces, 22,23 and multiscale approaches. [24][25][26][27] Multiscale approaches treat different regions of the molecule with methods of varying cost and accuracy to reflect their importance. 28,29 For example, one may use EOM-CCSD to describe the important region of the molecule while using molecular mechanics (MM), in EOM-CCSD-in-MM methods, [30][31][32] or DFT, in EOM-CCSD-in-DFT methods, 33 to describe the remainder of the molecule. Such approaches take advantage of the high accuracy of EOM-CCSD and the low scaling of MM or DFT to go beyond the size/accuracy limits of any one method alone.Density functional theory embedding provides a formally exact framework for performing multiscale calculations. This approach has been shown to be accurate for combining density functional theory with wave function theory. The key choice in density function theory embedd...

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“…The Manby and Miller groups proposed the use of the parameter-dependent levelshift projection operator (hereinafter the µ operator) as 45,[60][61][62][63][64]…”

Section: Absolute Localization Projection-based Embeddingmentioning

confidence: 99%

Absolutely Localized Projection-Based Embedding for Excited States

Wen

Graham

Chulhai

et al. 2019

J. Chem. Theory Comput.

119

View full text Add to dashboard Cite

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“…Here, E q WF [Ψ A ] denotes the total derivative of the subsystem A WF energy with respect to nuclear coordinate, which can be directly calculated using existing WF gradient implementations, andd A rel is the WF-relaxed density for subsystem A. For example, the MP2-relaxed density isd (27) which contains the subsystem A Hartree-Fock density, γ A , the MP2 density matrix, d (2) , and the solutions of the subsystem A Brillouin conditions,C AzCA, † . Eq.…”

Section: F Gradient Of the Total Energymentioning

confidence: 99%

“…For all geometry optimizations the number of LMOs in subsystem A is kept unchanged throughout the optimization. A natural way of enforcing this in future work is to employ even-handed partitioning, 27 although this was not needed in the examples studied here; the default procedure based on net Mulliken population sufficed to keep subsystem A unchanged. All geometries are optimized using the translation-rotation-internal coordinate system devised by Wang and Song, 83 which is available in the GeomeTRIC package.…”

Section: Computational Detailsmentioning

confidence: 99%

“…Projection-based embedding has proven to be a useful tool in a wide range of chemical contexts including transition-metal complexes, 19,20,24,27 protein aca) tfm@caltech.edu tive sites, 21,23 excited states [28][29][30] and condensed phase systems, 16 among others. [31][32][33][34][35][36][37] The development of analytical nuclear gradients for projection-based embedding will expand its applicability to include geometry optimization, transition state searches, and potentially ab initio molecular dynamics.…”

Section: Introductionmentioning

confidence: 99%

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Analytical gradients for projection-based wavefunction-in-DFT embedding

Lee

Ding

Manby

et al. 2019

The Journal of Chemical Physics

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Projection-based embedding provides a simple, robust, and accurate approach for describing a small part of a chemical system at the level of a correlated wavefunction method while the remainder of the system is described at the level of density functional theory. Here, we present the derivation, implementation, and numerical demonstration of analytical nuclear gradients for projection-based wavefunction-in-density functional theory (WF-in-DFT) embedding. The gradients are formulated in the Lagrangian framework to enforce orthogonality, localization, and Brillouin constraints on the molecular orbitals. An important aspect of the gradient theory is that WF contributions to the total WF-in-DFT gradient can be simply evaluated using existing WF gradient implementations without modification. Another simplifying aspect is that Kohn-Sham (KS) DFT contributions to the projection-based embedding gradient do not require knowledge of the WF calculation beyond the relaxed WF density. Projection-based WF-in-DFT embedding gradients are thus easily generalized to any combination of WF and KS-DFT methods. We provide numerical demonstration of the method for several applications, including calculation of a minimum energy pathway for a hydride transfer in a cobalt-based molecular catalyst using the nudged-elastic-band method at the CCSD-in-DFT level of theory, which reveals large differences from the transition state geometry predicted using DFT.

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“…[63][64][65][66][67][68][69] The use of subsystem orbital orthogonalization methods for exact DFT embedding was studied by the Manby and Miller groups through the use of a constant shift µ-projection operator. 40,41,[70][71][72] This µ-projection operator demonstrated impressive results and in a later paper, Kallay and co-workers suggested 73 the use of the Huzinaga 74-76 level-shift projection operator as an alternative to the µ-projection operator. Our group generalized the Huzinaga level-shift projection operator with a freeze-and-thaw localization scheme and demonstrated significant success using absolute localization on molecular and periodic systems.…”

Section: Introductionmentioning

confidence: 99%

Robust, Accurate, and Efficient: Quantum Embedding Using the Huzinaga Level-Shift Projection Operator for Complex Systems

Graham

Wen

Chulhai

et al. 2020

J. Chem. Theory Comput.

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Wave function (WF) in density functional theory (DFT) embedding methods provide a framework for performing localized, high accuracy WF calculations on a system, while not incurring the full computational cost of the WF calculation on the full system. In order to effectively partition a system into localized WF and DFT subsystems, we utilize the Huzinaga level-shift projection operator within an absolutely localized basis. In this work, we study the ability of the absolutely localized Huzinaga level-shift projection operator method to study complex WF and DFT partitions, including partitions between multiple covalent bonds, a double bond, and transition metal-ligand bonds. We find that our methodology can accurately describe all of these complex partitions. Additionally, we study the robustness of this method with respect to the 1 arXiv:1911.12449v1 [physics.chem-ph] 27 Nov 2019 WF method, specifically where the embedded systems were described using a multiconfigurational WF method. We found that the method is systematically improvable with respect to both the number of atoms in the WF region and the size of the basis set used, with energy errors less than 1 kcal/mol. Additionally, we calculated the adsorption energy of H 2 to a model of an iron metal organic framework to within 1 kcal/mol compared to CASPT2 calculations performed on the full model while incurring only a small fraction of the full computational cost. This work demonstrates that the absolutely localized Huzinaga level-shift projection operator method is applicable to very complex systems with difficult electronic structures.

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Even-handed subsystem selection in projection-based embedding

Cited by 45 publications

References 109 publications

Absolutely Localized Projection-Based Embedding for Excited States

Absolutely Localized Projection-Based Embedding for Excited States

Analytical gradients for projection-based wavefunction-in-DFT embedding

Robust, Accurate, and Efficient: Quantum Embedding Using the Huzinaga Level-Shift Projection Operator for Complex Systems

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