TD-DFT spin-adiabats with analytic nonadiabatic derivative couplings

Bellonzi, Nicole; Alguire, Ethan; Fatehi, Shervin; Shao, Yihan; Subotnik, Joseph E.

doi:10.1063/1.5126440

Cited by 14 publications

(10 citation statements)

References 75 publications

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“…In general, our work reinforces the attractiveness of building spin-adiabatic energy surfaces for studying spin-crossing reactions [15,[22][23][24][25][26] as well as the feasibility of computing SOC on the fly within the Breit-Pauli one-electron operator framework. [46,47] However, in order to build more smooth spin-adiabatic potential energy surfaces using the Breit-Pauli one-electron operator so that standard TS search and reaction pathway optimization algorithms can be utilized, more general methods to construct the spin-diabatic states need to be developed. Specifically, these methods would involve different molecular orbitals for different spin-diabats and thus require the solution of z-vector equations in the analytical gradient evaluations.…”

Section: Discussionmentioning

confidence: 99%

“…Specifically, we employed the Breit-Pauli one-electron spin-orbit operator, [9,39] which is also widely available for nonrelativistic quantum chemistry calculations. [40][41][42][43][44][45] Recently, the Breit-Pauli one-electron spin-orbit operator was also employed to construct spin-adiabatic excited states within both configuration interaction singles (CIS) [46] and the Tamm-Dancoff approximation to time-dependent density functional theory (TDDFT/TDA) [47] frameworks. Similarly, we will adopt the original Breit-Pauli one-electron spin-orbit operator, with the expectation that the use of full Breit-Pauli operator, [44] effective nuclear charges, [41] or mean-field approach [48] would reduce the spin-orbital coupling but retain a very similar picture for the reaction energetics.…”

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confidence: 99%

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Constructing spin‐adiabatic states for the modeling of spin‐crossing reactions. I. A shared‐orbital implementation

Tao

Pei

Bellonzi

et al. 2019

Int J of Quantum Chemistry

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In the modeling of spin-crossing reactions, it has become popular to directly explore the spin-adiabatic surfaces. Specifically, through constructing spin-adiabatic states from a two-state Hamiltonian (with spin-orbit coupling matrix elements) at each geometry, one can readily employ advanced geometry optimization algorithms to acquire a "transition state" structure, where the spin crossing occurs. In this work, we report the implementation of a fully-variational spin-adiabatic approach based on Kohn-Sham density functional theory spin states (sharing the same set of molecular orbitals) and the Breit-Pauli one-electron spin-orbit operator. For three model spincrossing reactions (predissociation of N 2 O, singlet-triplet conversion in CH 2 , and CO addition to Fe(CO) 4 ), the spin-crossing points were obtained. Our results also indicated the Breit-Pauli one-electron spin-orbit coupling can vary significantly along the reaction pathway on the spin-adiabatic energy surface. On the other hand, due to the restriction that low-spin and high-spin states share the same set of molecular orbitals, the acquired spin-adiabatic energy surface shows a cusp (ie, a first-order discontinuity) at the crossing point, which prevents the use of standard geometry optimization algorithms to pinpoint the crossing point. An extension with this restriction removed is being developed to achieve the smoothness of spin-adiabatic surfaces. K E Y W O R D Schemical reactions, spin-adiabatic surface, spin-crossing reaction | INTRODUCTIONIn most chemical reactions, the total electron spin is conserved. However, if a reaction involves high-spin species, such as oxygen ( 3 P) and nitrogen ( 4 N) atoms, molecular oxygen ( 3 O 2 ), and transition metals, [1][2][3][4][5][6][7][8] a change in the electron spin might occur during the transition from the reactant to the product. Such spin-crossing reactions are known to be enabled by the spin-orbit coupling (SOC) between different spin states. [9,10] While usually slower than their spin-conserved counterparts (especially in cases with a weak SOC), spin-crossing reactions can play an important role in biochemical processes, homogeneous/heterogeneous catalysis, energy storage/conversion, etc.In the study of spin-crossing reactions, one can explore either the spin-diabatic or spin-adiabatic potential energy surfaces. In the spindiabatic approach, the central task is to reach the crossing seam of two spin-diabatic potential energy surfaces, and then locate the minimum energy crossing point (MECP) on the crossing seam. [11][12][13][14] This is illustrated in Figure 1A for a triplet-to-singlet reaction. Once the MECP is found, Yunwen Tao and Zheng Pei contributed equally to this study.

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Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

Constructing spin‐adiabatic states for the modeling of spin‐crossing reactions. I. A shared‐orbital implementation

Tao

Pei

Bellonzi

et al. 2019

Int J of Quantum Chemistry

Self Cite

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“…For the systems with heavy elements where S is not a good quantum number, including complexes of third-row transition metals, lanthanides and actinides, it is desirable to carry out NAMD simulations in the spin-adiabatic basis with the NAC between the spin-mixed states driving the interstate population transfer. While such spin-adiabatic simulations are starting to emerge (25,(116)(117)(118), the progress requires interfacing NAMD with the electronic structure methods capable of calculating the analytical NAC between the spin-mixed states (119,120).…”

Section: Electronic Structure Methodsmentioning

confidence: 99%

Modeling Spin-Crossover Dynamics

Mukherjee

Fedorov

Varganov

2021

Annu. Rev. Phys. Chem.

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In this article, we review nonadiabatic molecular dynamics (NAMD) methods for modeling spin-crossover transitions. First, we discuss different representations of electronic states employed in the grid-based and direct NAMD simulations. The nature of interstate couplings in different representations is highlighted, with the main focus on nonadiabatic and spin-orbit couplings. Second, we describe three NAMD methods that have been used to simulate spin-crossover dynamics, including trajectory surface hopping, ab initio multiple spawning, and multiconfiguration time-dependent Hartree. Some aspects of employing different electronic structure methods to obtain information about potential energy surfaces and interstate couplings for NAMD simulations are also discussed. Third, representative applications of NAMD to spin crossovers in molecular systems of different sizes and complexities are highlighted. Finally, we pose several fundamental questions related to spin-dependent processes. These questions should be possible to address with future methodological developments in NAMD. Expected final online publication date for the Annual Review of Physical Chemistry, Volume 72 is April 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

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“…77 These observed behaviors contribute to important Peierls coupling for the intermolecular acoustic-like modes. A direct computation for the nuclear derivative for the electronic coupling is available nowadays, 78,79 which allows for direct computation for the Peierls coupling with any given vibrational mode, which would facilitate such characterization without having to scan for the nuclear degrees of freedom.…”

Section: Gas-phase Calculationsmentioning

confidence: 99%