Practical Post-Kohn–Sham Methods for Time-Reversal Symmetry Breaking References

Journal of Chemical Theory and Computation, Journal Year: 2023, Volume and Issue: 19(11), P. 3131 - 3145

Published: May 15, 2023

The applicability of reduced scaling algorithms based on auxiliary subspace methods for the correlation energy from random phase approximation (RPA) as well part self-energy obtained GW method is outlined time-reversal symmetry breaking Kohn-Sham (KS) references. updated allow an efficient evaluation RPA energies and quasiparticle molecular systems with KS references that break symmetry. latter occur, example, in magnetic fields. Furthermore, relativistic open-shell molecules also due to single determinant ansatz used. Errors reduced-scaling are shown be negligible compared reference implementations, while overall computational by 2 orders magnitude. Ionization robust even electronically complicated group trivalent lanthanoid ions. Starting energies, it subsequently light-matter interactions these can calculated using Bethe-Salpeter equation (BSE). Using combined GW-BSE method, absorption emission spectra a europium(III) complex including spin-orbit coupling.

Language: Английский

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Robust relativistic many-body Green’s function based approaches for assessing core ionized and excited states

The Journal of Chemical Physics, Journal Year: 2023, Volume and Issue: 159(4)

Published: July 28, 2023

A two-component contour deformation (CD) based GW method that employs frequency sampling to drastically reduce the computational effort when assessing quasiparticle states far away from Fermi level is outlined. Compared canonical CD-GW method, scaling reduced by an order of magnitude without sacrificing accuracy. This allows for efficient calculation core ionization energies. The improved efficiency used provide benchmarks ionized states, comparing performance 15 density functional approximations as Kohn-Sham starting points calculations on a set 65 energies 32 small molecules. Contrary valence prefer functionals with only moderate amount Hartree-Fock exchange. Moreover, modern ab initio local hybrid are also shown excellent generalized references calculations. Furthermore, core-valence separated Bethe-Salpeter equation (CVS-BSE) CVS-BSE convenient tool probe excited states. latter tested 40 excitations eight inorganic Results excitation and corresponding absorption cross sections found be in agreement those reference damped response BSE

Language: Английский

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Why Does the GW Approximation Give Accurate Quasiparticle Energies? The Cancellation of Vertex Corrections Quantified

The Journal of Physical Chemistry Letters, Journal Year: 2024, Volume and Issue: unknown, P. 12526 - 12534

Published: Dec. 13, 2024

Hedin's GW approximation to the electronic self-energy has been impressively successful in calculating quasiparticle energies, such as ionization potentials, electron affinities, or band structures. The success of this fairly simple ascribed cancellation so-called vertex corrections that go beyond approximation. This claim is mostly based on past calculations using within crude local-density Here, we explore a wide variety nonlocal polarizability and self-energy, first-order approximations infinite summations all orders. In particular, use vertices statically screened interactions like Bethe–Salpeter equation. We demonstrate realistic molecular systems two equation essentially compensate. further show consistency between crucial for obtaining properties. finally consider increasingly large clusters extrapolate our conclusions about compensation would hold extended systems.

Language: Английский

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Frozen Natural Orbitals for the State-Averaged Driven Similarity Renormalization Group

Journal of Chemical Theory and Computation, Journal Year: 2024, Volume and Issue: 20(10), P. 4170 - 4181

Published: May 15, 2024

We present a reduced-cost implementation of the state-averaged driven similarity renormalization group (SA-DSRG) based on frozen natural orbital (FNO) approach. The orbitals (NOs) are obtained by diagonalizing one-body reduced density matrix from SA-DSRG second-order perturbation theory (SA-DSRG-PT2). consider three criteria to truncate virtual NOs for subsequent electron correlation treatment beyond SA-DSRG-PT2. An additive correction is applied Hamiltonian reintroduce effects discarded orbitals. FNO method benchmarked 35 small organic molecules in QUEST database. When keeping 98-99% cumulative occupation numbers, mean absolute error vertical transition energies due less than 0.01 eV. Using same threshold, we observe speedup 9 times compared conventional nickel carbonyl with quadruple-ζ basis set. approach enables nonperturbative computations chloroiron corrole [FeCl(C

Language: Английский

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