∆SCF Dyson Orbitals and Pole Strengths from Natural Ionization Orbitals

Harb, Hassan; Hratchian, Hrant P.

doi:10.26434/chemrxiv.13365326

Cited by 2 publications

(2 citation statements)

References 56 publications

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“…64 In preliminary tests, we also carried out calculations using commutator and Converged electronic structures were characterized by visualization of occupied MOs and using a modified form of the natural ionization orbital (NIO) program by Hratchian and coworkers. [65][66][67] Further assessment was carried out by calculation of Δ-SCF results. Initial guess MOs were selected based on the ground-state, Hartree-Fock (HF)-optimized reference.…”

Section: Numerical Testsmentioning

confidence: 99%

Using projection operators with maximum overlap methods to simplify challenging self‐consistent field optimization

et al. 2021

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Maximum overlap methods are effective tools for optimizing challenging ground-and excited-state wave functions using self-consistent field models such as Hartree-Fock and Kohn-Sham density functional theory. Nevertheless, such models have shown significant sensitivity to the user-defined initial guess of the target wave function. In this work, a projection operator framework is defined and used to provide a metric for non-aufbau orbital selection in maximum-overlap-methods. The resulting algorithms, termed the Projection-based Maximum Overlap Method (PMOM) and Projection-based Initial Maximum Overlap Method (PIMOM), are shown to perform exceptionally well when using simple user-defined target solutions based on occupied/virtual molecular orbital permutations. This work also presents a new metric that provides a simple and conceptually convenient measure of agreement between the desired target and the current or final SCF results during a calculation employing a maximum-overlap method.

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Section: Numerical Testsmentioning

confidence: 99%

Using projection operators with maximum overlap methods to simplify challenging self‐consistent field optimization

et al. 2021

Self Cite

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“…65 Analyses for converged electronic excited states were facilitated by using a modified form of the natural ionization orbital (NIO) model by Hratchian and coworkers. [66][67][68] Using the NIO model, converged electronic excited states were verified by visualizing the natural orbitals of the difference densities relative to the ground state. This scheme is analogous to the Natural Transition Orbital model of Martin, 69 but directly separates electron-hole pairs from orbital relaxation contributions in the difference density from a ∆SCF set of calculations.…”

Section: Condon Vibronic Spectral Calculationsmentioning

confidence: 99%

Comparison of Linear Response Theory, Projected Initial Maximum Overlap Method, and Molecular Dynamics Based Vibronic Spectra: The Case of Methylene Blue

Taka

Gowland

et al. 2021

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Simulation of optical spectra is essential to molecular characterization and, in many cases, critical for interpreting experimental spectra. The most common method for simulating vibronic absorption spectra relies on the geometry optimization and computation of normal modes for ground and excited states. In this report, we show that utilization of such a procedure within an adiabatic linear response theory framework may lead to state mixings and a breakdown of the Born-Oppenheimer approximation, resulting in a poor description of absorption spectra. In contrast, computing excited states via a self-consistent eld method in conjunction with a maximum overlap model produces states that are not subject to such mixings. We show that this latter method produces vibronic spectra much more aligned with vertical excitation procedures, such as those computed from a vertical gradient or molecular dynamics trajectory-based approach. For the methylene blue chromophore, we compare vibronic absorption spectra computed with: an adiabatic Hessian approach with linear response theory optimized structures and normal modes, a vertical gradient procedure, the Hessian and normal modes of maximum overlap method optimized structures, and excitation energy time correlation functions generated from a molecular dynamics trajectory. Due to mixing between the bright S1 and dark S2 surfaces near the S1 minimum, computing the adiabatic Hessian with linear response theory time-dependent density functional theory with the B3LYP density functional predicts a large vibronic shoulder for the absorption spectrum that is not present for any of the other methods. Spectral densities are analyzed and we compare the behavior of the key normal mode that in linear response theory strongly couples to the optical excitation while showing S1/ S2 state mixings. Overall, our study provides a note of caution in computing vibronic spectra using the excited state adiabatic Hessian of linear response theory optimized structures and also showcases three alternatives that are not as subject to adiabatic state mixing effects.

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∆SCF Dyson Orbitals and Pole Strengths from Natural Ionization Orbitals

Cited by 2 publications

References 56 publications

Using projection operators with maximum overlap methods to simplify challenging self‐consistent field optimization

Using projection operators with maximum overlap methods to simplify challenging self‐consistent field optimization

Comparison of Linear Response Theory, Projected Initial Maximum Overlap Method, and Molecular Dynamics Based Vibronic Spectra: The Case of Methylene Blue

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